Maintenance Tool sometimes hangs at "Preparing meta information download..."

Updating feature works unreliably for me. Sometimes Qt Creator shows me info about update right away, but often when I press "Check for updates" it just checking it indefinitely. Same thing with Maintainance tool. It connects to my account, but when I choose "Update components" it just shows me "Preparing meta information download..." indefinitely. 

It started happening a long time ago, I just reported it now, because as I said, it's really inconsistent behavior. I just tried several times to update and it didn't work, then it suddenly connected and I updated, and now I can't connect again.