Tokina atx-i 100mm F2.8 FF Macro Q&As

Hi! I have purchased a new Tokina 100 mm atx-i lens a few months ago and was using it with multiple Nikon's bodies without any issues until a few days ago. The behavior is the following: I would use the lens for 30-40 minutes for continuous macro shooting and then I would start getting  F-- error on my Nikon camera. I have tried cleaning lens contacts - does not help. I can reproduce the issue on different Nikon bodies.  Reattaching the lens helps sometimes (not for long though) but very...