Thanks Techman and Andy for the suggestions, I had tried both before, and again just now, with these results:
Trying the rt-clk Restore Device on the devices that dont work gives the "would you like to proceed" modal, I respond OK, and nothing happens. There is still an exclamation mark in the device tree view. And still no device control for those devices.
On the full PLM reset, I did the Restore Modem (PLM), and I see the "system busy" progress for what looks like way too short of a time. I can see briefly "reset PLM", but no comfort that link tables are being downloaded.
This is a new USB PLM I bought to go with eisy - I was paranoid that either or both of the serial U413S I used with my isy994 were defective in some way. ... I didn't do the "power up the PLM with the reset button depressed" dance, is that possibly why Restore PLM doesn't seem to be working?
I've attached my event log for the actions described above just now. I suppose I could nuke the devices and start over, but some of the devices are in hard to reach places that are difficult to get into reset mode. Thanks so much in advance for any next step suggestions.
ISY-Events-Log.v5.8.4__Sat 2024.09.21 09.14.21 AM.txt