I have a git repo with a single submodule sub/x. (This submodule does not contain any submodules of its own.)
In the superproject's repo, the output of git status shows the following (unstaged) modification
modified: sub/x (new commits)
If I now run
git submodule update
...on the superproject, the following line gets printed to the terminal (and nothing more):
Skipping submodule 'sub/x'
After this, the output of git status on the superproject remains as shown above, unchanged.
(Ditto if I add --init to the git submodule update command.)
Q: How can I determine why git submodule update [--init] skips the sub/x submodule?