Yep, I'm having this problem as well.
Anyone can replicate this bug very easily—fly straight and level, lock up any available target, do an aileron roll in either direction and watch your lock break.
This appears to be happening to everyone, not just me and the OP. Every person I've discussed this issue with has also experienced it (nearly 15 people now).
This is a hugely significant bug, one that myself and others consider to be a game-breaking bug for the JF-17. It simply cannot be used reliably for air-to-air engagements in MP on the current 2.5.6 patch. Worse still, many of the MP servers have already switched to 2.5.6 and so this prevents us from simply rolling back to 2.5.5 or stable and using that until a fix is ready.
If additional logs/tracks are needed I've got some to contribute, but this is a pretty clear and obvious bug that is easily reproduced in-game.
