Perhaps there's something fundamental I'm doing wrong here, but...

Cropping 3:2 aspect (ie non-1080p) still images or video, using Proxy files, play fine in the Project Monitor but then fails to render identically. 


STEPS TO REPRODUCE
1. Create a new 1080p project and load a series of 3:2 still images to the Project Bin.
2. Make some of them proxy clips.
3. Crop them all to fit the 1080p aspect and drop them onto the timelime for a 10 sec video. 
4. The Project Monitor plays as you would expect it to. Everything fits the aspect.
5. Render it, and the resulting output plays differently. 
   The non-proxy images fit, the proxy ones have black bars left/right. 
 

OBSERVED RESULT
The rendered .mp4 file is not the same as displayed in the PM. Black bars on left/right. 

However the proxy images do appear to have some small crop but it looks like it's the proxy crop values applied to the original image without any scaling.


EXPECTED RESULT
The rendered file should be the same as displayed in PM

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Linux Mint 19.2 Cinnamon
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: Frameworks 5.61.0
Qt Version: 5.12.4 (built against 5.12.4)



ADDITIONAL INFORMATION
Also fails in 17.12.3 (the default for Linux Mint 19.2)