RDS FOR MySQL and the Replication Filters

Folks,

Some days ago, I needed to add an a. a to one of my replicas to filter out one bad database.table creating problems for the replication stream. Today, I don't need to filter anymore as the data has already gone, and I need to remove the a. a added to the replicate-ignore-table, part of the RDS instance parameter group. When I remove the a. a or the string from the replicate-ignore-table field using the Console, I receive an error "Empty value found in form parameter replicate-ignore-table".

I feel like it should be possible to have no filters added to the replicate-ignore-table, right? Is that expected? How can I resolve this? Thanks for any help.