SSIS master key on Replica

Hi!

I have an Azure 2016, SQL 2016 2 node always on configuration with SSISDB in the availability group.

My packages work on the primary node, but on the replica I get the following error:

Please create a master key in the database or open the master key in the session before performing this operation. 

I have run the following but my packages still fail

OPEN master Key decryption by password = '<Password>' -- Password used when creating SSISDB
ALTER Master Key ADD encryption by Service Master Key

I have enabled always on support for SSIS on the primary node.

Any idea what I'm missing?

Thanks,

Zoe