Can anyone search on Shared Channels?

To clarify, file search is broken. Posts do appear in search results in the Teams app.  I am fully focused on file search, as we have done a massive migration to Shared Channels and now none of our files are searchable.  

jcgonzalezmartin, are you sure it's a shared channel that you are testing?  Could you post a screenshot from the SharePoint site with search results?  This is what I get on every shared channel, SharePoint site:

The crawl logs show the files have been crawled.  And searching for "*" would generally return everything in the search index.  But we get zero results, regardless of the user.   

I have been a SharePoint developer for 15+ years, so it's frustrating being kept in the dark on an issue and not having access to fix it myself.  My guess is the authentication provider changes on Shared Channel sites broke security trimming in search.  I just don't understand why it would work for some tenants, but not others.