Windows filesystem mount point directories are not shown in the filepicker. You have to show hidden files to show them. That's wrong because a filesystem mountpoint isn't a hidden file. Also i had to triple check why the mount isn't showing up, and verify with the terminal that the mount is indeed there. Showing hidden files was a wild guess and is not intuitive.

To reproduce:
# 1. Mount Windows filesystem /dev/sdw to /media/test
mount /dev/sdw /media/test

# 2. Open /media in the file picker

Expected:
Directory test should be shown.

Actual:
No directory called test is shown.

Workaround: Enable hidden files to show test directory