Not rendered QQuickView with Wayland shared memory fallback

We are getting a reproducible issue when creating various QQuickViews in combination with a QtWayland based compositor in Ubuntu 18.04.

The attached example (ViewerTest.zip) creates three views with three different colors. When executing the example with -platform wayland as argument and using the official QtWayland example qwindow-compositor as compositor then randomly no, one or two of the QQuickViews are not rendered but are created. The attached videos (success.ogv and fail.ogv) demonstrate the issue.

So far the issue is only reproducible with Ubuntu 18.04 (with libwayland-dev 1.14.0-2). When using Ubuntu 17.04 (with libwayland-dev 1.12.0-1) everything works as expected.