You may get an error on log reader agent failed with following error:
Cannot execute as the database principal because the principal “dbo” does not exist, this type of principal cannot be impersonated, or you do not have permission.
reason could be due to some activity the owner of the publisher database is gone (UNKNOWN) can cause this issue.
change the owner of the job usinga
EXEC sp_changedbowner ‘sa’
and it should work.