On all versions of kernels:
4.14.71-ti-r80
4.19.94-ti-r42 - console version
4.19.50-ti-r20 - buster 10
I found many posts can be found on this issue through google. Not just on BBBw, it is also on many other Linux platforms. It seems to me all answers are pointing to bad SD cards. But all these cards are good, at least they are R/W able on my Linux PC, and on our production boards. In my opinion, at least it on both ends (software driver and hardware ).
Weird thing is that one BBBw board was bad ( I had marked the SD card reader on the BBB, which was a few months ago, But now it is GOOD.) Believe or not, it is not I had mis-labeled or something. Because all of old BBBw went bad, I had to order a few more.
I think I am OK, now. because we have added SD card in our new rev boards.
Best Regards,
David