I can recommend this one from Mathorn brand:
https://mathorn.com/en/tethering-cables/tethering-5m-2/mtc-531/
It works nice with my GFX50s - see the video
so if i'm shooting uncompressed 16-bit RAW files it takes a significant amount of time to write to card. Got the high end UHS II cards, and this does not happen with burst shooting, only single frame shots. what setting am i missing that causes this to happen?
The Tentacle Sync Timecode tool is the one I tried. I couldn't get it to work. But that is probably my fault, not the software. I seemed to get a file, but I couldn't turn it into anything meaningful.