Importing Catalog endless Silverlight "Loading" circle

Hi,

When updating the catalog in a endless silverlight "loading" circle appears. no task is started. the catalog is not updated. Also tried manually download catalog.cab (1.7mb file) and importing it via select a catalog source also nothing happens. OME version 2.4 with the 2.4.0.1 hotfixed

Done so far:

- Made sure i'm using a ome full admin account

- Made sure there's no proxy settings configured at all

- Tried from several systems and windows versions on IE11

- Restarted OME server

- Cleared IE & Silverlight cache

- Last successful catalog update was February 2018 ..

- The Download Catalog test in the troubleshooting Tool says Catalog Downloaded succesfully.

Getting a little desperate... Anything else i can try?

Thanks in advance!