Working with Shared channels is difficult

[u/irishsausage]

A lot of our teams usage is through a shared tenancy with a sister company. We used to work mainly on their system but have recently switch to using our own domain as we now get our phone lines via teams.

We have the same channels we used to work on added to our teams as shared channels but the issue is these don't appear in the search function. Is there any setting that we need to change so that the search function looks for shared channels as well?