is your midi interface an inexpensive 1×1 usb midi cable?
many of those only transmit note on, prg change and CC but not
sysex. just a hunch
Nope, it’s a MOTU Ultralite. sysex works fine on my setup with Midiquest XL but it’s a pain to use.
Edit: Thought I figured out but no, just managed to make ctrlr receive sysex data, still not able to send it.