Incorrect display of files or directories in the file tree if the directory or file name contains +:
However, there are no such problems in the MODX file browser.
There is no bug in MODX3 either.
More information here -https://community.modx.com/t/creating-a-directory-which-ends-with-a-doesnt-load-in-modx-dashboard/3135
Possible explanation:
Maybe it has to do with the fact, that a plus sign in the query string of a url represents a space.
If the manager makes a call to .../connectors/index.php?action=browser/directory/getList&id=gl+/&type=dir, the id-parameter is possibly interpreted as gl plus a space.
MODX 2.7.3
This issue has been mentioned on MODX Community. There might be relevant details there:
@rthrash Yes, I indicated this in the description of the issue :)
Pssst, @rthrash is a bot. Don't tell anyone tho.
Possibly related. If you create a folder named [[++holidaytheme]] in the file system the MODx folder tree (left column) will create an infinitely nested loop of those folders.

https://community.modx.com/t/file-folder-looping-or-something-bug/3253
It fixed by merged PR
Most helpful comment
Pssst, @rthrash is a bot. Don't tell anyone tho.