No network drives when adding attachment

We recently migrated to Windows 8.1, we had no problems with Notes client so far untill a user complaint that she couldn’t find our data directory i: when she want to add an attachment in her email.
(as workarround i told her to use the direct path \server\map) After some digging and creating new profiles. I now have the same problem and we both have the correct network paths when we open our explorers

Does anybody have an idea what this can be?

Subject: Questions

Is the problem with the mapped drive not showing only happening with Notes? What if you open a browser or other application, is the mapped drive showing for other applications?
What is the exact version of your notes client?

Subject:

Thank you for your response.
The mapped drives are only not showing in Lotus. I just tried it with skype and lync and outlook and they show the mapped drives like normal.

We currently are working with 8.5.2 and upgraded some machines with 8.5.3 and version 9.0.1 and on all versions the problem occurs.

Looking forward to your response