Bit-Locker protected Flash drive becomes read only

I use Flash drives protected by Bit-Locker to save some confidential information.

Now I have a problem:

The drive can be unblocked by entering the password, no problem, and the information can be read.

But is it read-only, no information can be written to it. The error message says the drive is protected against writes.

This began to happen a few days ago, after the last Windows 11 update.

I appreciate any ideas to solve this.

Does it work on another computer?

1. It may have an incorrect read-only flag. Run diskpart:

2. Or the USB's flash controller has detected cell errors, and locked the drive from new writes. You can read old files, but Windows won't risk you writing new or updated data to it.

I have tried two Windows 11 computers [HP Mini PC, Lenovo ThinkPad] - the same problem in both.

I have also tried several UFD drives - all good-quality Samsung Bar drives. Same problem in all of them.

The diskpart method doesn´t work. I had already tried it (suggested by Google AI).

But I tried in a Windows 10 computer and all went well, no problems with the same UFDs.

So I think it is related to Windows 11.

Since it's happening on multiple machines and multiple drives, but not on Windows 10, my best guess is that there's a bug in how Windows 11 re-checks the BitLocker policy after a recent update. Even though the drive is properly encrypted and unlocks without any issues, Windows may briefly "forget" that it's protected and switch it to read-only mode as a precaution. Windows 10 doesn't seem to have the same issue, possibly because it handles the check differently.
You could try refreshing the BitLocker policy, then unplugging the drive, restarting your PC, and plugging it back in (ideally using a different port) before unlocking it again. That should force Windows to re-check the drive properly and may restore write access.

I have just this minute clean installed 25H2 26200.9457 (same as the OP uses) and tried some of my old BitLocker to Go USB drives. They both open and allow changes to files to be made. I can also save new files to the drive.