Flow Rate (FR) defaults to 999%

I recently flashed the firmware to Marlin 1.1.9 (from Printersolid) on my CR10s. I left everything at default and all went fine.

The problem I have is that when I connect Octoprint the flow rate will randomly default to 999% (not always). This can happen whether I boot octoprint first then turn on printer or if I turn on printer first then boot octoprint.

When it happens, I can still set the printer to print from Octoprint and it will bring the bed an nozzle up to temperature and will then indicate that its printing on the printer's LCD panel but does not actually print.

I can change the flow rate back to 100% if it defaults to 999% but this doesn't make any difference.

The only tiem I can get my printer to print using octoprint is when the flow rate defaults to 100% at start up of bothe the printer and octoprint. If it defaults to 999% at any time when staring the printer and octoprint then I can't print anything.

Does anyone know what might be causing this? It's really annoying.

Thanks in advance for any help.

Sounds for me like there is something wrong with your marlin config. I would suggest to try a vanilla marlin with the example config and see if the problem persists.
You get it here https://github.com/MarlinFirmware/Marlin

Logs, especially a serial.log might shed some light on this with regards to whether it has anything to do with what OctoPrint sends to your printer on connect or not.

I head some unexpected behavior on my stock Ender 3 Pro BLTouch firmware like it was trying to center X and Y without G28 when connected to usb. Also it was extremly sensitive electromagnetic interference (when I turned off my fluorescent tubes on the ceiling the usb connection was interrupted).
These problems where gone after flashing vanilla marlin 1.1.9.

So I thought it might help you too.