K Edge mount compatibility.
I have been using a K Edge XL mount for my Garmin without issue for a while and decided to get a combo mount so I can put my GoPro on the bottom. Issue I have now is that there is no screw sized holes to connect it. If I remove the inner plastic bit that is the part the Garmin sits in I have 2 small screw holes that it sits in at the 12 & 6 o'clock positions , but the other two holes are much larger and not threaded. Am I missing something or are K Edge selling incompatible items? I could buy an XL with the combo but that costs over £50. I would have thought I had just bought that but in 2 parts and it would be complete but it's not. Anyone have the XL combo and know if I am missing something?