Adobe Document Cloud error download/upload file on Windows v2018.011.20038

Normally logged in, and Document Cloud can load my file lists. But I can't open/download any of my file in Document Cloud. A window pop up saying Adobe Document Cloud is still working on your last operation.

And the most important part is I can still rename the files.

What I've tried:

1. Repair the installation.

2. Uninstall/re-install the program.

3. Check the settings according to this https://forums.adobe.com/thread/2445193?q=adobe%20document%20cloud%20is%20still

Please fix this REAL QUICK, and tell me what should I do! Personally I take Acrobat PDF Reader as daily reader and this is completely ruining my experiences with it.