LDAP accounts with apps

Our instance is using OpenLDAP for authentication. Most mobile apps work fine with this setup but we are having an issue with one app crashing. Looking at the database, I see that the oc_users table is empty except for a couple of local admin accounts. Inside of Nextcloud in the Users section, I see all of the LDAP users. In the tables I see them in oc_accounts and oc_ldap_user_mapping. Not sure how some apps are set up as far as what they are tying to the user id. We have a few users that were local accounts and then associated with LDAP accounts. Since the old accounts existed, there are new accounts with their LDAP username appended with an underscore and four random digits. For some reason on one mobile app, only this users are having an issue where the app crashes. So I am trying to see what the typical process is for this authentication to see if this other app needs to be modified to handle this oddity.