I just discovered inadvertently a bug with the Crop: source filter.
Start a new project 960x540
Import 2 vertical images, the first in 720x1280 and the second in 337x557.
Place these images on the timeline and apply the Crop: Source filter to each of them to crop them. Check the “Center” Checbox
With the first image, the operation is correct, the “Center Offset slider” can be adjusted from -640 to +640.
With the second image, the “Center Offset slider” cannot be set to negative values. All values between -279 and 0 are inaccessible.
Is it due to the size of the second photo which is smaller than the one of the project?
Or to its dimensions which are odd numbers (337 and 557)?
The attached folder contains the mlt file and the 2 images.
OS X 10.11.6
Test image verticale.zip (572.6 KB)