Since Windows 8 is running on my notebook (clean install, no upgrade), I can't rename folders or files on mobile devices running Windows Mobile or CE and connected with ActiveSync (via USB) anymore (or even create new ones with a custom name). The explorer will ignore my input and use the previously entered name (or something like "New Folder" for newly created directories).
Step 1: Right click in Explorer > New Folder > Enter a name

Step 2: Confirm with enter key

Does anyone have a clue on how to fix that?
UPDATE
The devices are shown in Explorer like this:

Update: Neither upgrading to Windows 8.1 nor reinstalling Windows 8.1 changed the behavior described above.