It took me a while, but I realized something that was a bit "off"...
The edge connector seemed a bit narrow, so I had to compare.
Turns out the pitch has changed for some reason. Here I'm comparing the edge connector with the one from the MMC64 (left).
Thankfully, the most expensive part, the DPRAM, was not yet soldered.
Oh well, time to order a new set of boards. Good thing OSHPark delivered so quickly.