You have recently upgraded Vibe to a newer version like 4.0.6 or later. Since this time GW users who had a Vibe integration enabled do not get any folders populated from their Vibe workspace. A user adds his credentials but nothing else happens.
With newer versions of Vibe, a default TLSv1.2 is set. If you were using some older client builds that still use old Vibe integration libraries, those cannot handle TLSv1.2 protocol. A request for login from GW client simply gets declined.
This has been fixed in newer 18.2.x client builds. You will need some recent 18.2.x client build (min version 18.2.1-135732). Open a new SR and request the latest 18.2.x client build.