Hosting from QT

I am hosting relatively successful using JUCE in a bigger QT application.
However, the plugin GUI window (a JUCE window for simplicity) doesn’t really react, sometimes individual events seem to be passed through, in both directiuons, but most of the time it’s stuck.

I added the ScopedJuceInitialiser__GUI to my engine, therefore a MessageManager is running (verified with Timers that run with no problem).

Is JUCE now running a separate message thread or is it hooking into QTs QEventLoop?
What do I need to change so the window reacts normally?

Edit: this is on a Mac Mini M1 / 16 GB RAM and 12.4 Monterey with an UAD Apollo (thunderbolt) in case it matters