KeypadLinc Button disappears from scene

A scene activated by a v.36 KPL secondary button suddenly stopped doing its thing after working for years. It's an "After Dinner" scene that we use quite often so whatever happened to break it is recent.

When I looked at the scene in question the KPL button that was the scene's controller was no longer part of the scene. Re-adding the button to the scene fixed the problem but its disappearance concerns me. I have not messed with the KPL in question for quite a while, and it's been even longer since I messed with the scene in question. That said, I have added and modified other scenes involving other devices within just the last few days.

Has anyone seen / Is there a known issue with KPL scenes getting mucked up like this when one is configuring scenes in other device(s)?

I can't say I've seen this before but I have had other weird things happen to KPL's before. See list below. While the cause remains unknown or unclear for the issues below, it appears in some cases to be related to the KPL having been restored.

While the KPL in this case has been restored before, it was a long time ago and it did not / does not exhibit the problems reported above. (The non-toggle mode and LED brightness problem are still there for another v36 KPL right next to it.)

After fixing things I did check the device links table and compared it to what the PLM link table has for it and everything is fine with the 60 or so device links. In hindsight I wish I would have checked the two before re-adding the button.

Am using a 994i with the latest firmware and my PLM has 415 links - well below the max, I believe.