Prop2 Eval Boards all need a mod to fix SD/Flash brownouts
The reset circuit of the Eval Boards feed into the enable of the "Common VIO" voltage regulator. This has the unfortunate side effect of, when triggered by comport DTR toggle, a brief shutdown of supply to the Flash EEPROM and, if present, the SD card. The supply capacitor droops to about 1.5 volts before being regulated again.
I'm recommending the removal of R802 and fitting of R801 as the fix.
Here's a scope screenshot of a DTR toggle at beginning of program download:
Blue trace is pin P60, with SD card pull-up, so represents the supply to the SD card.
Pink trace is VIO volts V5663.
Orange trace is P2_RESN.