I linked to a bunch of jpegs and cut them into my sequence.
When I went to do some moves with frameflex I got mixed results.
Sometimes, having changed the format to '16:9' - so it filled the raster - this showed up as working in effect edit mode, but back in source/record I was seeing black bars as if it were still set to 'Custom' (where it fits the whole jpeg into the raster, with letter or pillarbox).
Sometimes, having changed format to '16:9' and added a couple of keyframes - adjusting the scale handles in the GUI would result in a fully squashed image. Undoing and using the scale slider in the effect editor was the workaround. But still when switching back to source/record mode the DVE move was not visible. Stepping back into the effect and adjusting position slightly and back out again would fix it. Sometimes.
Loving this as a means of accessing and putting moves on stills - but it still needs a bit of TLC I think