I can’t get my Samsung EVO Plus 128 GB to work with the FP4 either. The FP4 doesn’t manage to format the SD card as portable storage: It starts, briefly shows a progress bar at 20%, then immediately reports success, but not rightly so. Then a permanent notification appears saying “This device doesn’t support this Samsung SD card. Tap to set up in a supported format.”
I have also tried formatting the SD card (exFAT) using Windows and putting files on the card that way. But when I plugged it back into the FP4, it showed the same notification as above.
(Edited: I will #contactsupport to say: Please let me know if and how I can assist in resolving this issue.)