I am having a similar issue. Has this been solved? I am on a Raspberry Pi with no screen, connected to Anycubic i3 Mega Ultrabase. Image file name: "Repetier-Server-Image_0_90_0_v9.img" I could send a command with the Heated Bed GUI but it would not display a temperature. The screen on the printer would show it is heated. Please see link for screen grab: https://i.imgur.com/6r9SUSF.png I started a print since temps were good.
It so happened this was my first print with Repetier-Server and it failed, not sure why, but that is not the issue here. After I canceled the print, I was able to click "Off" for the hot end and bed. The display on the printer indicated they were cooling down. I clicked the "0" and entered 60 on the bed control. Actually I clicked the left side of the displayed zero and entered "60" which displayed "600", I pressed Del, but the zero on the right would not go away, so I pressed backspace to get rid of the middle zero and hit enter. Bed temp went back to heating and controlled to target. I captured the message for debug:
1:02:38.974: N458407 M105
1:02:38.978: ok T:76.6 /0.0 B:60.8 /60.0 @:0 B@:127
After this I tried to enter "0" on the heated bed section of the control tab. Heater stayed on. I clicked on the bed icon on the top right and clicked "Off" and the bed turned off and started to cool down. Throughout the whole process, the Heated Bed display nor Heated Bed graph never showed a temperature or a setpoint. At least I had good adhesion.
Thanks
clayrev