Unable to select multiple messages on mac

Using Monterey, I'm unable to either Cmd or Shift select multiple messages on my mac. Using the Cmd and Shift keys results in only selecting a single message, which forces me to have to delete them one by one, which is very time consuming. I'm guessing this is only part of a larger issue as I can delete the same messages, in bulk, from my iphone, ipad, mac mini, all of which are on the same account, but the messages are never removed from my mac. Any advice would be appreciated.

I have turned off/on; removed/reinstalled the associated accounts on my mac with no effect in linking to the other devices or with the ability to select multiple messages.