Can't upload / download files in GrabCAD Workbench

Hello ,
I have had this problem for several days when I try to upload / download files to Workbench. "An internal error has occurred. Please contact support@grabcad.com if you are experiencing problems or you see this error again."
I sent an email to support@grabcad.com , but I haven't received a response from them yet. Has anyone had a similar problem and how did you solve it?