Can confirm I was running into the issue "Vendor command returned unparseable data." after updating. I was reinstalling and setting up Jellyfin from scratch too. Thought I broke something else lol. Found out via intel_gpu_top in Terminal that my GPU was working, Transcoding, Ramdisk, ffmpeg all up and running. Its a Chrome [ Version 131.0.6778.69 (Official Build) (64-bit) ] bug. Open up firefox and the dropdown works.