2 partitions on a Samsung T7?

Hi! I have a 2 TB Samsung T7 shield, and originally partitioned to a 1.9TB APFS, and a 0.1 TB ExFat, with the idea, that can use most of it with the Mac (High Sierra), but if I need to move stuff to a PC, I will copy that from the APFS side to the ExFat side... Worked a bit, not then it stopped recognizing/mounting the 1.9 part :(

I have stuff on there, so would try to avoid reformatting the whole thing. Any advice would be greatly appreciated!