Have a TinyScreen+ project. Can't upload to it from Windows 10.

When I plug in, it doesn't get recognized as "Unknown Device" but rather Com3.

Try to upload to Com3 from the Arduino interface results in "No Device Found" even though I'm getting flashing for Rx on the board itself.

It should come up as a COM port in Windows, not an unknown device. Can you try the 'reset'(stay in bootloader) instructions at http://theowatch.com/start/troubleshooting/reset-tinyscreen/ and let me know if that helps?