@Daniel, have you tried adding some qDebug() lines in the QT5 libraries to see if we actually get the touch events and finally ungrab the device? (the code is in src/plugins/platforms/xcb/qxcbconnection_xi2.cpp)
Also, it would be interesting to see what XIGrabDevice and XIUngrabDevice return.
@Daniel, have you tried adding some qDebug() lines in the QT5 libraries to see if we actually get the touch events and finally ungrab the device? (the code is in src/plugins/ platforms/ xcb/qxcbconnect ion_xi2. cpp)
Also, it would be interesting to see what XIGrabDevice and XIUngrabDevice return.