This was an issue a couple of years ago, got fixed and seems to have crept back beginning with the June 6th nightly build. The issue is where with LibreElec (generic version on Intel), not with Kodi on Windows, that many addons, including the LibreElec configuration addon are spewing classes left in memory errors. This is likely due to a problem with the Python garbage collection process. A thread was started in the Kodi forum. I just wanted to raise it here, in case the developers were unaware. I had posted some logs there but this is very easy to reproduce.
Thanks,
Jeff