If you see "Notifcation skipped," then either you're outside of the configured modes or there are no inactive devices to report. In your case, I believe it's the latter; it's supposed to say why (e.g., no inactive devices), but I see a typo in the code that would make that not happen.
Regarding the notification "delays" or schedule, I suspect there isn't really a problem. The "8:54 PM" thing, along with the date, that you're setting in the notification text is the "Last Activity At" metadata from the device on Hubitat. You can see this on the device page, and that is the same information Device Activity Check is accessing. (This makes sense if you're using the default "inactivity detection method" of "last activity time" and would be more apparent in the notification text if you had multiple devices listed; it doesn't make a ton of sense for "presence"-based detection given that generating that event causes the device to be marked as having activity, but I digress.)
Finally, not that you asked for advice here, but if you want it anyway: my guess is that you're dealing with a Z-Wave device that only "wakes up" once every day or maybe even every other, and your inactivity time threshold is too low to capture that. Decreasing the device's wakeup interval (some have a way to set this via a Z-Wave parameter; not sure what other options Hubitat provides here besides what the driver might do by default) or increasing the threshold in the app (of course, risking that there may actually be a problem in the meantime--but pretty much the case with any such device) are the only two ways I see around this--assuming my guesses about the problem, should you consider the device being in the notification to be one, are correct.