I use the local use database authentication in APM for a few policies and I have noticed in the logs I see this error tons.
Master Decrypt failed for user %localdatabaseuser% with error ''
Note it lists which local database user but I have seen this will all of the handfull of local database users I am using since the backend application dosen't intergrate with AD.
It doesn't seem to be causing any issues just filling up my apm logs so would like to get it to stop if that is possible.
I am on versoin 18.104.22.168
And just for reference and maybe you've already checked it but here is the Manual Chapter about Local User Database: