Problem has been solved, although the solution doesn’t make a lot of sense to me.
A few years back I was having some issues with my computer and as a last ditch attempt to sort it I made another account to log into on Windows 8, which for some reason sorted the problems I was having then.
I remembered this and I logged back into my old account, started Resolve, played some cinemaDNG… problem solved. I honestly have no clue how or why that would even sort the playback issue out but it has.
Thank you for the help guys, it’s very much appreciated!!