https://forums.openqnx.com/t/topic/23558
Can you try the last suggestion (sin fd) and see if you ran out of file descriptors (fd’s)? This seems to be a likely culprit.
The other thing is to try a plain ‘mount’ command and see if somehow your filesystem is now mounted as read only (I think a plain mount will show whether it’s mounted as RW or R).
It’s good you haven’t rebooted yet so we can run through a lot of things.
Tim