💥 Pins 3 and 4 of IC were swapped which lead to non functional "Spindle VFD Speed Control" part.
Thanks to Gerssi for reporting!
To fix this issue in already existing PCBs you may cut the two wires going to IC5 pin 2 and 3 on the PCB and use a small external wire to connect them accordingly.
Fixed in revision 4:
Wrong in revision 3:
