Doppler uploads failing every other time


I just got around to try my doppler, what a wonderful hardware combo!

I however have one recurring issue with my uploads, every other upload i attempt fails at around ~15% and becomes unresponsive, not showing up as a usb device or nothing.

However, i randomly discovered a workaround by entering some kind of bootloader mode by double clicking the reset button in a specific sequence (is that documented anywhere?) - after that i can program it just fine again.

Is this expected behaviour, do i need to reset it into bootloader mode every time it has been running something?

i always double tap reset to enter the bootloader. i have this issue on all samd51 boards, so maybe looks something is wrong in bootloader or bossac.exe