Database inaccessible from cluster

Hi all,

We have a SQL cluster of 2 nodes, and all of our databases have an Availability Group. Yesterday I noticed that 1 particular database cannot be expanded from within SQL Mgmt Studio, when I'm connected to the cluster address.  When I try to expand the DB, I get this error:

Any other DB can be expanded without any issues, and I can browse the tables.

The only difference is, that this particular DB is currently hosted by the secondary node in the cluster.

But that shouldn't make any difference, I suppose...?

What could be the issue here?
Thanks !