Trouble with MIDI In after non-XT to XT HW Upgrade

Some months ago, I’ve soldered the Shruthi XT Panel PCB. Everything seems to work, besides MIDI Input.
I resoldered all joints around the 6N137, including R15-R18 and checked the Diode Orientation, but I still cannot
get MIDI IN to work. PS: With the non-XT panel + corresponding firmware, MIDI was still functional.

I’m attaching a photo of the section.

Update: I replaced the 6N137 optocoupler, but still MIDI in appears dead.
I also resoldered the MIDI_RX pin of the Microcontroller Socket.

Did you not socket the chips? also, it looks like your chip is surface mounted or there’s a lot of solder around the legs.

Have you done a firmware upgrade? This could have messed with the settings, in particular the MIDI channel #.