This is hardly imaginable, as the PCB grounded connections should all share a common PCB connection (you can see the little “bridges” from the soldering pads to the common ground).
I made it work by connecting the islands to common ground with two extra cables. Broke a germanium diode while trying to clean a hole to use for permanent connection. I’m kind a had it with this build. I’m have no idea how to get the diode out again or clean that ground hole. But the pedal worked. Thinking about just getting another kit and start over. Fixing those tiny boards is close to impossible. Here is a picture of of the extra cables going to the island that is not connected to input output ground either.
Glad it finally worked. The diodes should not be much of an issue. You can take them off with a self-heated desoldering pump (e.g.Vellemann VTDESOL3), which also empties the holes and normally leaves the solder pads in place. New diodes are really cheap to order (I always order some additional ones and keep several types in my DIY box). If you might later want to try different ones it is always a good idea to not solder them directly to the PCB but to use sockets in between.