DIN-TRS is not actually “standard” to my knowing, vendors failed miserably to unify TRS midi, several different pinouts are existing out there, and you need to be sure that your particular adapter is the one compatible with your particular device, as you can expect some catch here.
Dwarf should use “type A” according to another TRS forum thread. (TRS to MIDI pinout - #9 by malfunction54)
If I had to troubleshoot that, I would start with taking din pinout diagram, type A trs pinout diagram, and test the actual adapter wiring with multimeter beeps to be sure that everything is connected properly.
P.S.
Also, I do not see mentions of MIDI Display plugin in your post. If you have not tried it yet, you can route MIDI data to it, to see in webui if the input part works at least.