MIDI Fighter Classic LEDs quit after soldering

I have a MIDI Fighter classic board (I think it's #32/500 - the ink has worn off a little) that I have put into a project box, and I've attached 4 arcade buttons to do the "bank" switching.

All the buttons work fine, as confirmed in Ableton Live, as well as checking with the snoize MIDI monitor.

However, for some unknown reason, after soldering in the pins, the LED lights stopped working on the main 16 bottons - except for two of them - the top-right-most button (button #4, if we're going left-to-right, top-to-bottom), and the second-to-the-left button on the second-row-from-the-top (button#6 if we're going left-to-right, top-to-bottom).

I've got photos and the snoize report data here it that helps: https://tinyurl.com/yjnhvm5w

The MIDI Fighter utility says my firmware is up-to-date, and the LEDs all worked before I soldered the new buttons in, so I know I did something - I just don't know what I did, or it it can be rectified. I'm hoping someone here has an idea.

Thanks!

Edit: Looking at the board a little more carefully, it's stamped that it is a MF-MK1.2, if that helps anyone at all