Did some small scale testing with a friend...
While we didn't come across this issue, we did find that the JF-17 interferes with the F-16s datalink. A JF-17 with datalink enabled in master mode would cause any contact shown as "unknown" to the JF-17 (ie any contact it has not IFFed) to be removed from the F-16s datalink/HSD
It did not seem to affect the F/A-18 at all, all datalink contacts seemed to stay on no matter what in that one.
This was only with 2 players though, so there could be other interactions with more players, or 2 or more non-hosting players