Sorry, I was out of town and just not able to weigh in...
I saw all the same things... Weirdly, it began working only after I started going through each device and manually doing a refresh... After about 7 or 8, for some reason, the app started working and it has been working fine since... I really believed it was a platform thing as it started right after an upgrade...
My suggestion is try to manually refresh some devices and see if it start working like it did for me. 
Yes, I had been doing that for over a week, and then when I saw you reporting the same symptoms at the same time, I figured I should speak up.
I did uninstall the app completely, and then reinstalled. I only created one group which contained only "refreshable" devices, both Z-Wave and Zigbee.
After adding about 6 devices, it worked perfectly for 24 hours. Afterwards I added about 18 more devices, and the random "failures to refresh" returned.
Although the affected devices were random, some occurred consistently. I removed the 3 most problematic devices, and the remaining 21 devices suddenly worked perfectly. I am currently removing and re-pairing these devices to see if I can continue to make use of them in the future.
The only theory I have is that when these devices were "refreshed", they transmitted a data storm that randomly blocked the replies from all the other devices.
I love this app, and it has always been dependable. I'm looking forward to putting it back into full operation soon.
I was just thinking about that
I expect the refresh commands need to be metered with 200 or so between commands. Maybe more of there's a bunch.
The code is open and modifiable, so for anyone who is curious: that is, in fact, that is exactly what it's already doing. 
You can try increasing that interval (or others) to see if it helps, but if running "Refresh" on the device itself doesn't help (sounds like that was the case at least once above?), I'm not sure anything an app can do will help, either.
In my situation, sending a "refresh" from the device page did work, but the "refresh" from Device Activity Checker seemed to be ignored. I say "ignored" because the logs confirmed the command had been sent, but the last activity time on the device page did not update.
Thanks for the the info on changing the pauseExecution time. I may experiment with that, but I am reluctant to change anything because I know the app has always worked great in it's natural form.
When I first installed the app, I received many "false" failure reports, which actually showed as updated in the device Last Activity time. Running a 2nd check just seconds later, resulted in no failures being returned. I had changed the waittime previously to resolve that issue successfully.
I am going to consider my personal problem as resolved. Not completely resolved, but certainly not an issue with DAC.
Thanks everyone for your advice and suggestions.
I just noticed a couple devices are not shown in the spot to check to refresh. One is a sonoff button and the other a sonoff temp sensor. I have them checked to be monitored and get a report on the button if I have not pushed it.
They probably don't have the refresh capability or command.
^ This. I haven't seen a battery-powered Sonoff Zigbee device yet that is actually "listening" for anything from the hub (beyond the time of initial pairing), so these drivers probably don't have the command because it wouldn't do anything.
I would also recommend being selective about use if this feature in the first place, which I mention because (I think some people use it too much 
and) the fact that any particular device in your larger list doesn't show up shouldn't be a cause for concern on its own. But when it does happen, the explanation is going to ultimately relate to the commands the device offers.
Long time user of this fantastic app. One request. Would it be possible to have the Time for the report to be sent an option? I only want it to run when a switch is turned on. This way, I can easily turn off the daily report if I don't want it while on vacation.
The time field is optional, assuming that's what you mean. If you've already set something there, you should be able to clear it (possibly browser-dependent how).
You are correct. Trying again and it worked.
Hello,
Since the latest update broke my monitoring rules, i am checking this app.
The first thing i've noticed is that you cannot select a device attribute to monitor, like power attribute from a shelly device. The device reports every few seconds. I need to monitor the power because to this shelly plug i have connected a freezer. At some point it was accidentally turned off and i didn't notice. You can imagine the rest so it is critical to monitor the power attribute to be sure it actually works.
The second thing, is there any option to send an alert immediately? I want to get a notification right away, not daily at a given time.
For motion sensors it works well.
A simple RM rule could do that for you.
Trigger
power change
action
wait elapsed time
Send notification no power update in whatever time you waited above.
I do this for my garage freezer, I also watch the energy level and voltage. If none of those change in 3 hours it sends me an alert
Already created another rule after the initial one broke.
It is a nice feature to have.
For power moitoring, I recommend this app - it's designed for that, and it works well.
I'm not well-qualified to explain the intentions of Device Activity Check (DAC), but I'll give my $0.02 here...
I find DAC super useful for big-picture device health -- IMO, it does an great job of balancing being a simple & lightweight app that still has wide reach for alerting me to an unresponsive device in a reasonably timely manner (e.g. battery dies in one of my rarely-used window sensors - I'd otherwise potentially not notice that for months since my window sensors have wonky battery reporting, but they do routinely report a temperature [so no temp-report activity w/in 24 hrs = dead battery in that case]).
If you need immediate (or very specific) status alerts, DAC isn't intended for that -- there are other options (such as the app I linked above) that can better handle unique/specific needs.
Indeed it is very easy to use.
But i would like a more complex app. For simple notifications i also use the built in app. I does the same thing and also has some interesting features like repeating notifications every n minutes and for a limited number of times instead of sending a report at a fixed predefined time.
The built in app also does lack features, such as triggering notifications based on presence variables not sensors.
I am not complaining about the app at all, just pointing out possible improvements.
I also tend to use built in apps for futureproof functionality.
I have temp sensors in both the upstairs and downstairs refrigerators and freezers. If the temp raises above 35 in either refrigerator or above 10 in either freezer, a siren sounds and all heck breaks loose, can’t be letting my ice cream melt…
Download the Hubitat app
