If you open settings, little cog in bottom right corner the time line resolution setting should be there at the top of page, try using a lower resolution and see if that helps to start off with. Doesn’t affect your final render.
Hi Nigel, I use Sony AVCHD with no issues with Resolve, my Sony PXW-X70 stores them in a folder called Stream, its buried quite deep – different file structure to yours but I would dig in to the Clip folder and search in there.