Serial monitor flashing

Hi all

I'm part way through a polargraph project that I'm going to run off my laptop running Linux mint.

I'm hunting down a strange issue where the serial monitor is flashing or greying out about once a second even with no MC connected to a usb port.....

I've change the dialout permissions thing:

Its fine connecting to the IDE on windows so the server sketch and cable is fine?

As far as I can remember the IDE was working fine before?

video of the flashing :
flashing serial monitor

any suggestions, I've no idea.... :confused:

I see it flashes at about 1 Hz, which sounds similar to:

though in that case the "flash" is caused by disconnecting a different port, so not exactly the same.

The first thing I would recommend trying is updating to Arduino IDE 1.8.12. It may be that the bug you're encountering has been fixed since the release of the Arduino IDE 1.8.10 you're using. If it still occurs with 1.8.12, you might try the test build provided by ArduinoBot in the comment thread of this pull request: