Right clicking symbol freezes Creator

I use Qt Creator 4.4.1 with a generic project (C+), and sometimes I also open files that are not marked as part of the project (but they're in the same directory hierarchy).  I use the C+ code model.

Fairly often, right clicking on a symbol causes Creator to become unresponsive. The mouse pointer is stuck as an i-beam, and Creator does not respond to any clicks.  The menu opens, but using Quit doesn't close the system.  I must use Force Quit from the dock.  Yet the OS doesn't consider Creator unresponsive because it does not show me the Force Quit option automatically.

While this problem happens regularly, there is some randomness to it, and I cannot reproduce it at will.  Right clicking the same symbol may work 4 times without problems, and the 5th time it'll cause a hang.