Messages app has stopped showing a list of conversations, and started showing only attached items.

Hi jpdemers,

Wondering if this is for recent conversations , or maybe just older conversations are being automatically deleted.

You might want to check your settings ... eg: messages may be being deleted after 30 days, if so, maybe select longer.

Change General preferences in Messages on Mac – Apple Support

ie: Messages > Preferences, > General > Keep Messages

Or, if that's not the answer for you ...

You can change what you see in the left sidebar:

eg: Try this

Click "Window" in the top menu bar, and click "Go to next conversation" in the drop-down window

The conversations should appear in the left sidebar, with a conversation open ready for use.

or experiment ...

Click the search (magnifying glass" to change the left sidebar

While there, click the small round icon on the right of the search entry-field to change again

Hope this helps put you more in control.

All the best :-)