Well nothing known or obvious comes to mind. But then there is ambiguity in your post which I need to get clear first.

Your topic title says you are ‘repeatedly losing’ messages.

Your post just states that the inbox indicates there are 6 but only shows 3.

So are you sure there are genuinely 3 messages lost (as the title implies) or that the count is incorrect (as the post sort of implies)?

Thanks for your response. There are genuinely 3 messages lost. Could this be some kind of indexing issue?

I’m really not sure actually but doubt any sort of indexing issue.
Would you be willing to ask the person/people on the other end of the PM thread if they see all they should be seeing?

Oh – and perhaps just in the spirit of intelligence gathering are the ‘missing’ messages ones you sent or received?