Hi Dale
Quick Answer
The HyperDecks only
PLAY files with the same CODEC set up for recording.
Let's say: if the HyperDeck is set up in
ProRes, it will
only play ProRes files, even if you have .DNxHD or .H.264 files on the SDcard or SSD.

Just try set up the hyperdeck with different codecs to play your clips
NOTE:Test it exporting from Resolve using the preset: H.264 HyperDeck.
Don't use folders, just leave the files at the root
I hope help