So, I think my latest mod has solved completely the dropping of GPS. It is rather a bother to do, but now get 9-10 sats while recording in 60fps mode. Had to completely disassemble to get the cable out from the camera to the board. Used copper tape in strips to cover all section of the flat cable, then covered again in the kapton tape to insulate. Also did the small jumper on top of the board between the small PC board and connection to the main pc board. Fired it up and GPS lock is so fast is amazing. This is not a mod for the feeble, but if you can do neatly, it should solve all the GPS locking issues. I have also done the mod at the top of the copter to shield over the GPS as others mentioned, but that produced poor results for me. Now we are flying with 9 sats and even got 12 tonight during test run. Turned recording on/off/on, etc. and no issues at all.

Could you show some photos of the procedure you did please?