user-reported phishing emails

Less than concreteness to offer here, but here goes...

Typically when the Inbox is greyed out, the message is thought to already be in Inbox.  Sometimes that's not the case and the UI is clearly flawed.  They introduced that "Show all response actions" slider sometime in the last year or two, and that helped to unlock the options when the UI is confsued.  Even still the UI is confused often.  But it totally could be that the emails in your screenshot's case, are already sitting in Inbox (or some other folder that is not Junk/Deleted Items).

When somebody reports a message as Junk/Phish, the message is moved to the Deleted Items folder.  When the verdict comes back as "No threats found", the message is NOT moved back to Inbox.  As it relates to the Take Action menu where we can move items, to Inbox for example - I believe (cannot guarantee) it will only let you move to Inbox if the system hard previously moved it to Junk or Quarantine.