User issues notifications change without user action


I setup a internal gitlab community edition (omnibus) on the company I work for about 3 years and been keeping it updated and running well, except for about the end of 2019 I receive some reports about users not stop receiving notifications on the issues they follow.

I can’t pinpoint the problem but it seems the notification switch on the issue, without user acting on it or closing the issue, sometimes turns to inactive.

After the user activate it again, some time later it turns off again.

Anyone experience this behavior? Is something I’m missing? Is there any logs I can check?

I read the documentation and check the normal productions logs but can find any problem. Currently running Gitlab 12.10.1.

Thanks for any feedback…