Just a continuation of this thread - I can’t post in that thread any longer as I’m over my new-user 3 post limit, also it’s been marked as solved (it was only half solved).
I believe I’ve identified the bug in TrueNAS Scale and have opened a bug., which may be helpful for anyone that is trying to graph a slave UPS.
Other than hacking the built-in chart script, I don’t see a solution/workaround, so hopefully development can pick this up… at the very least, the log spam needs to be stopped…