19.05.2018, 10:01
Sorry but you are going around in circles a bit.
I have already shown that your dev version 2018-05-16 does not only not display preview but also fails to encode.
I give the evidence again. Screenshots and debug attached
1) tried load mp4 file direct into Hybrid used no filters and it crashed.
2) closed Hybrid, restarted and loaded same mp4 but this time tried preview no filters.
Window opened for a fraction of a second then closed.
3) closed Hybrid, restarted and loaded mp4 again but this time set Tweak filter
No flashing window or preview
I have already shown that your dev version 2018-05-16 does not only not display preview but also fails to encode.
I give the evidence again. Screenshots and debug attached
1) tried load mp4 file direct into Hybrid used no filters and it crashed.
2) closed Hybrid, restarted and loaded same mp4 but this time tried preview no filters.
Window opened for a fraction of a second then closed.
3) closed Hybrid, restarted and loaded mp4 again but this time set Tweak filter
No flashing window or preview