I have been looking around the config files etc. to see if I can pinpoint where the issue is. So far no success.

In the etc/fstab I have /dev/mmcblk0p1 /home/user/MyDocs vfat defaults 0 2

The fstab is generated by the script etc/event.d/rcS-late. I looked into this script and didn't notice anything unusual there.

The config file for user's filesystems seems to be the etc/default/mount-opts. I have there lines for "home-opts=" which I don't think applies for MyDocs case. The second line says: fat-opts="noauto,nodev,noexec,nosuid,noatime,nodiratim e,utf8,uid=29999,shortname=mixed, dmask=000,fmask=0133,rodir". I did try changing the fmask to 000 and rodir to rwdir, after which I mounted MyDocs, but it did not help. (Then I changed them back to original.)

There is another config file /etc/default/mount-opts.dpkg-dist, but there I have pretty much the same options except the fmask=0000, which should work fine?

The file etc/profile file I have line "umask 022" but when I changed it to "umask 000" it did not fix the problem. (Then I changed it back.)

The simplest workaround at this point is to umount /dev/mmcblk0p1 and then remount it using this command:
mount /dev/mmcblk0p1 -o dmask=000,fmask=000

In other words the mount command finds the all the correct default options from somewhere. It only needs manual overrides for dmask and fmask values.

Maybe this gives enough details for someone with detailed file system experience to pinpoint where the issue might be?

EDIT: Before someone points out the space before the last "e" in "nodiratime", it seems to be created by this forum: In post edit mode the space doesn't exists.