MP 1.3.49 doesn't recognize a Ph2.1 board for update

I just installed 1.3.49 release and have the problem that I can’t update my Pixhawk 2.1 anymore. It simply won’t detect and recognize the Ph at the beginning of the update.
Otherwise MP works well, I can connect through USB, read and write parameters, HUD and all displays work seamlessly. So it seems not to be a driver issue.

I then downgraded back to the 1.3.48 version and update worked as usual.
I then re-updated to the latest release 1.3.49 and the detection of the Ph failed again. Since I frequently updated Arducopter during the AC beta testing with 1.3.48 and prior betas w/o problems I assume a defect in the current release of MP.
@Michael_Oborne any idea?

Setup: Win32bit laptop with the latest Win10 upgrades installed.

please make sure you have the correct comport selected before the upgrade.
I will be fixing this but this is the workaround for the moment.