I have several Pro Micro clones.
This morning I uploaded a sketch into one of them (that was previously unprogrammed, so it stayed in Bootloader mode) and when I wanted to upload the sketch a second time, the problem began:
When I now run the reset procedure for Arduinos with integrated USB (open the COM port of the Pro Micro for example in PuTTY at 1200 bps and close it again), the LEDs start flashing rapidly and the Arduino disappears from the Windows Device Manager.
Hover for a (slightly annoying) image:
So then I grabbed a second, identical Pro Micro and uploaded the Blink sketch into it. It was also previously unprogrammed. The sketch executed, but when I now do the reset procedure, it exhibits the same behavior now (flashing LEDs).
I can still upload sketches just fine, by setting the COM port to a different (arbitrary) COM port to prevent the reset procedure from reaching the Pro Micro and resetting the Pro Micro manually after starting the upload procedure.
This only happens with the 3.3V/8 MHz variant, not with the 5V/16 MHz variant. I have selected the appropriate variant in the IDE.
How can I repair the automatic reset function?