One of the possible issue is not working ETL process, once database owner account is disabled or deleted, due to the fact that ETL works as database owner account.

Luware recommends set database owner to sa for all LUCS/TM databases in order to avoid ownership problems.

How to check database owner:

SELECT owner_sname = suser_sname( owner_sid ),*
FROM sys.databases
WHERE database_id = DB_ID()

If you decide you want to make SA the owner on a database, run this T-SQL command:

ALTER AUTHORIZATION ON DATABASE::ReplaceThisWithYourDatabaseName to sa;

Executing ALTER AUTHORIZATION command requires database owner permission.