I’ve just come across this. Currently it seems that only staff can use the bulk PM actions. However, the option of selecting PMs is also displayed to users but once a PM is selected no actions appear. I’m sure that in the past there used to be an option to archive / move to inbox when selecting messages as a user?
steps to repro:
- Go to your messages
- Press the list icon on top left (circled in image above)
- Select some messages. No other buttons appear to choose what you want to do with the messages.