Very strange problem...
 

This has happened a fair few times and reported by too many members (as well as checked by me logging into various accounts) for it to be a user oriented bug:

Occasionally posts made are visible to some members but invisible others. These post come from accounts with no restrictions. There doesn't seem to be any reason for it (infact I didn't even know it was even possible).

This has only happened in the last month after upgrading to 3.8.5

W.