Hi Rainer,
Would you mind trying this out for me?
In the folder where you have installed arcgis, navigate to:
runtime_sdk/qt100.5/sdk/ideintegration/argis_runtime_qml_cpp.pri
and remove line 125 which should read as: -L/usr/lib64 \
runtime_sdk/qt100.5/sdk/ideintegration/argis_runtime_qml.pri
and remove line 111 which should read as: -L/usr/lib64 \
runtime_sdk/qt100.5/sdk/ideintegration/argis_runtime_toolkit_cpp.pri
and remove line 80 which should read as: -L/usr/lib64 \
runtime_sdk/qt100.5/sdk/ideintegration/esri_runtime_qt.pri
and remove line 96 which should read as: -L/usr/lib64 \
You will need to close then reopen Qt creator, and do a fresh build from clean. If this does work do let me know.
Kind regards,
Neil