So, I'm having the same problem.
Using D1 mini, and a real small sketch (to exclude any software errors on my side)
VM is version 2020.910.8
VStudio Community 2019 is V16.8.2
void setup() {
Serial.begin(38400);
}
void loop() {
Serial.println("*");
delay(500);
}
Switching to an Arduino Uno works fine, so it seems it's related to the combination of the board I have and the one that I choose in the settings.
Also I have been able to upload software and run the Debugger, but for some reason that stopped working.
So, currently it sometimes works but most of the time it doesn't.
Sometimes, but not always, I get the additional message "User Experience: The serial debugger was delayed waiting for an incoming line of data. [...]"
I tried:
* Clean solution and rebuild
* DTS off and on (and also RTS)
* Serial speed down to 9600
* Use Serial1 instead of Serial
* Manually matching the Remote/Local speed in VM
* Selecting other boards in VM that seem the same (Wemos D1 R1, LOLIN(Wemos) D1 R2&mini, LOLIN(Wemos) D1 mini Pro, LOLIN(Wemos) D1 mini Lite). Even the 'Generic ESP8266 Module'.
All to no avail
So, how to proceed?