I still have the ISY994, which has been running fine up until last night. I have certain schedules that are supposed to happen automatically, like outside lights coming on at a certain time, shutting off at certain time, etc. All of a sudden last night I noticed they weren't on. When I physically hit the switch, it works fine, but trying to use the app or desktop page, nothing works. It thinks certain devices are on when they aren't, and even when I try to turn anything on or off, nothing works. My license hasn't expired yet, and I'm still very new to this system so I don't want to accidentally break anything without getting advice first. I will try unplugging the ISY994 while waiting for responses, but figured I'd post here first in case there are other ideas. Is this a sign I should get rid of the ISY994 and switch to the new product they use?

How old is the unit? I could be that the SD card, where all of the automations are stored, has become unseated or is going bad. Check the below link to docs on this topic.

You can first use the docs to find where the sd card is located, take it out (994 unplugged). Rub over the contacts with an eraser, wipe with rubbing alcohol, dry, reinsert and try again.

https://wiki.universal-devices.com/ISY-99i/ISY-26_INSTEON:Replacing/Formatting_an_SD_Card

I've had the house for soon to be 6 years and it's been here since before that, so I imagine it is fairly old. I will definitely try the SD card trick too. When I did unplug it and plug it back in, it now says it is in Safe Mode which i know is when the system can't communicate with the PLM for some reason

Actually, i think I figured it out! I checked the PLM and it was slightly unplugged so I just plugged that back in. Fingers crossed!