Can't cross compile QtQuickControls 2

Frime

Hello!
I have now successfully cross compiled and installed Qt 5.15.2 for the Pi Zero.
Afterwards I built and installed qtdeclarative with the freshly built qmake. build and install worked without any issues.
Now when I try to build the QtQuickControls 2 qmake says:

Running configuration tests...
Done running configuration tests.

Configure summary:

Qt Quick Controls 2:
  Styles ................................. Default Fusion Imagine Material Universal
Qt Quick Templates 2:
  Hover support .......................... yes
  Multi-touch support .................... yes

Qt is now configured for building. Just run 'make'.
Once everything is built, you must run 'make install'.
Qt will be installed into '/home/friedemann/raspi-zero/qt5pi'.

Prior to reconfiguration, make sure you remove any leftovers from
the previous build.

running make fails with following error:

Some of the required modules (qtHaveModule(quick)) are not available.
Skipped.

I'm a bit confused. QtQuick (qtdeclarative) is definitely build and installed..
but can't be found for some reasons.
Any idea how to fix this? Thanks!

Frime

I had to copy the content of the mkspecs folder from qtbase/qtdeclarative/mkspecs/modules to /qtbase/mkspecs/modules ... I have no glue what went wrong here, but it works now.