Group Changing to Not Logged I

Hello, we have a strange issue, and we are having trouble tracking it down. It happens on many/ most of our M2 stores, and we’re not sure why.

Occasionally, and seemingly randomly, one or more users’ customer group will change to “Not Logged In”. This manifests itself by showing no group in the customer grid (and not allowing a user to log in due to store restrictions).

Basically, I’ve been running the query below to check every day and manually moving those users back into the group that they should be in.

select * from customer_entity where group_id = 0

Has anyone seen this before or have any advice? We can’t seem to track it down as we can’t see anything (like a log) that shows it happening.

Edit: Missed a letter in my title – it should say Not Logged In (obvi)

Edit2: I’ve gone through all of our stores and determined which stores are experiencing this issue and comparing 3rd party extensions across them. The ONLY extension that is on the stores having this trouble and not on the others is Mirasvit Store Credit, so we’re looking into that. If anyone uses that extension and has this issue, please let me know. Thanks!