I just had a thing happen with Sunset in C7/2.2.3.145.
I have a switch to turn on at Sunset -60 minutes and off at 11:30 PM.
It had been working for a while.
Today was the first day of Standard Time, (Spring Ahead/Fall Back).
It turned on almost exactly an hour too early (according to Accuweather for my zip code).
I turned it off manually, and it came on at the correct time.
Weird.
Daylight savings time maybe didn't schedule correctly? It will probably work right tomorrow though.
Don't mean to brag, however.... mine worked as designed
Ok, I have the stick now. I ended up getting one from Zooz.
Silicon Lab site is not allowing new user registration for some reason. Tried different machines browsers (Safari, Chrome), same issue. I will try again tomorrow with a hope that their backend is fixed.
Btw, is PC Controller app Windows only?
Yes. PC Controller is Windows only. The rest of SimplicityStudio doesn’t have that limitation.
But you can run it in a virtual box.
If it's not against their EULA, can someone share the installed/executable for PC controller? Their site is still having issues and not allowing new account registration. To open a support case or to post in their community, all requires an account. Same issue as earlier.
I am still not able to create an account at sillabs and can't contact their support w/o the account either. Can you please share the issue on their forum on my behalf. Here is the video walkthru of the issue.
Sunset bug rears its head again (in 2.2.5.127).
Today is end of daylight saving here in NSW (Australia) and all my simple automations fired 1 hour early.
Which is what I have - I assume this hasn't been fixed yet?
Current firmware is well past that (2.2.6.137).
So has the bug acknowledged by @gopher.ny been fixed between then and 2.2.6? I didn't see anything in any of the release notes unless I missed it.
EDIT : is this it? " * Simple Automation Rule-1.1: Fix before sunrise/sunset."
All I know is that it works correctly for us each morning. C-7, 2.2.6.137.
Normally works fine very day for me too in my (older) version. It's just today that is our transition from DST.
It may be an issue for U.K. Australia that is not present in U.S.
I'm in Australia 
I think there are still some latent DST change bugs in the hub. We got most of them resolved, but evidently not all.
DST is a pain in the butt. I've had issues when I first started with WeMo devices and their rules. Then with ST and initially with HE but I must admit, not so much now.
I've taken the view that things may go off kilter for one day but resolve themselves the next day. (Usually). 
Not ideal but I think we have more pressing issues going on at the moment. 
Unfortunately there will always be pressing issues 
I noticed that no other Australian users reported the same issue so probably as @672southmain said it may have been to do with my older firmware. I've updated my hub in the interim and will report back in 6 months if it persists!
Won’t be same firmware by then, so the test will be inconclusive.
Download the Hubitat app
