Thanks for sharing this part of the design, it will help me troubleshoot my problem (tonight french time).
Another question that can be related. Are all holes all vias? Because sometimes tin is not going through the two PCB sides. Can be tricky to solder the other side (example: for ICs).
Have you done the HV calibration (click button while tubes are showing 888888) yet or are you still running in test mode (tubes counting)? I believe "clock not found" is normal when the clock is in test mode.
Look into it later when the dust is clearing off the crater.