When using C++ custom components and then

import QtMultimedia 5.0
..

MediaPlayer

The Qt Designer randomly stops working, it get blank content window altough it can be used as GUI editor.

Screenshot attached.

CONSOLE LOG:

$ QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
Process finished: QProcess(0xb8370a0, name = "EditorProcess")
Process finished: QProcess(0xb7fe388, name = "PreviewProcess")
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
Process finished: QProcess(0xb817b48, name = "RenderProcess")
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
qrc:/stateseditor/stateslist.qml:400: TypeError: Cannot read property of null
qrc:/stateseditor/stateslist.qml:168:17: QML Image: Failed to get image from provider: image://qmldesigner_stateseditor/baseState-2
Process finished: QProcess(0xb8315d8, name = "EditorProcess")
Process finished: QProcess(0xb802268, name = "PreviewProcess")
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
Process finished: QProcess(0xb81ad88, name = "RenderProcess")
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
QIODevice::write: device not open
qrc:/stateseditor/stateslist.qml:400: TypeError: Cannot read property of null
qrc:/stateseditor/stateslist.qml:168:17: QML Image: Failed to get image from provider: image://qmldesigner_stateseditor/baseState-4
qrc:/stateseditor/stateslist.qml:400: TypeError: Cannot read property of null
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3
QPainter::begin: Paint device returned engine == 0, type: 3