Loosing code highlighting after 3-4 hours of working

Sometimes it is loosing highlighting of objects in editor. It's showing it like it's not included. The object that going to be loosen unpredictable. Every time new one. I have usually opened 3-4 Qt Creator windows within different files opened. 

hIt's might be connected to this issue explained in this thread on forum https://forum.qt.io/topic/105562/q_property-from-official-doc-creating-error-why

Only restart Qt Creator helping and it is very annoying (my own emotions).