https://support.microsoft.com/en-au/topic/kb4488036-fix-repl-schema-access-wait-issues-when-there-are-multiple-publisher-databases-on-the-same-instance-of-sql-server-2016-and-2017-88e9f49f-c48b-29ea-b711-8f0838fcf460
KB4488036 - FIX: Repl_Schema_Access wait issues when there are multiple publisher databases on the...
FIX: Repl_Schema_Access wait issues when there are multiple publisher databases on the same instance of SQL Server 2016 and 2017