CallKit call blocking extension automatically disables occasionally

I have an app with a CallKit call blocking extension. Generally it works fine, but on some devices it occasionally becomes disabled by itself (well, in fact by iOS I guess) after a while – so user has to go to Settings and re-enable it again manually. However, there is no any visible reason for such behavior: the volume of blocked phone numbers data is small enough (the app works even with larger datasets most of the time, so it shouldn't be a memory issue), numbers are sorted in a right order (ascending), there are no duplicated numbers etc. It is also quite hard to reproduce the problem. It feels like something from "outer world" interferes with the extension (another app with extension?), but there are no proofs.

What may be the reason of such auto-disabling and how to avoid that?

Any help would be appreciated.

Thanks!

from CallKit call blocking extension automatically disables occasionally