Cannot connect to QML Emulation Layer (QML Puppet) what triggered it?

[Niconi]

I see people have this problem too, is it true by reinstall qt will fix it? because some of them said it not totally 100% fixed, but before I want to reinstall Qt I have question, what triggered it? why this happened?
Win10, VS2017
note: this is happened to me after i play with Qt example projects, before that from what i remember i never have this problem in qt 5.9.

Update 1: After restarting my laptop the problem is gone, I don't know why
Update 2: After I running the example project (Gallery Project) the problem is appears again :(
Update 3: After restarting my laptop again the problem is gone, and after playing with my practices project that qml puppet didn't appear, but I'm to afraid touching example project, I'm tired restarting my laptop :/

[Moved to Tools ~~ @Wieland]

[Tim.Jenssen]

please try a current snapshot: https://download.qt.io/snapshots/qtcreator/4.5/4.5.0-rc1/

and if there is still a problem, please create a bugreport