Unable to modify MagTag file system contents

***Souce***
Forums, https://forums.adafruit.com/viewtopic.php?p=980542#p980542

***Arduino board***
MagTag

**To Reproduce**
Steps to reproduce the behavior:

1. Choose any of the following actions
2. rename `secrets.json` to `secrets.old`
3. edit `secrets.json` (using notepad, exiting notepad) to have API key, username, SSID, and password
4. copy (from host) new `secrets.json` over existing file
5. Attempt safe removal: right-click the safe removal icon in taskbar, and choose to eject the USB device
6. Wait 30+ seconds
7. Either press reset button on MagTag, or slide power switch to off position for at least 3 seconds

**Expected behavior**
The file volume appears, and reflects the action selected above that modified secrets.json.

**Actual Results**
The first boot flashes neopixels purple for <1 second.
No serial port is enumerated, and no mass storage appears.
At this point, if use reset button again (or power switch), WIPPER volume will reappear, but with original, unmodified contents.

Also noteworthy: The "Safe Removal" attempt never completes. It's almost as though the device is failing all write commands, and thus rejecting the QUERY_REMOVAL until the cache is flushed ... which never happens.

**Additional context**

Adafruit.io WipperSnapper
Firmware Version: 1.0.0-beta.67
Board ID: magtag
MAC Address: 7C:DF:A1:17:8E:28

tinyuf2-adafruit_magtag_29gray-0.16.0
wippersnapper.magtag.1.0.0-beta.67.uf2

No source file or test is named. Start by reproducing the failure on the MagTag with the listed WipperSnapper and tinyuf2 firmware, then trace the firmware's USB mass-storage and filesystem write handling. Done means edited secrets.json survives reboot and the WIPPER volume reappears with the modified contents.

Written by the indexing model from the issue text.