Hello, My post was 156 you can see it on my activity and now its only 98 how that happens I just clear my cache to change my avatar then I saw my post was only 98 and I heck my post it dosent deleted My post is there on thread.
I suspect they have been having a cleanup on the boards, so you may have had a few posts deleted. You will know when the next activity update happens, that should adjust as well.