Hi,
The output resolution depends on the size of the face in your source photo, not the source photo itself.
If the face does not take up most of your 4096x4096 photo, then there may not be enough detail for a 4096x4096 of the UV map, depending on the UV map.
There should not be any regression in the latest version; please let me know which product and which versions you are comparing, and with which mesh.
You can email your example image to me: 'feedback' at '
facegen.com' and I can take a look at it to see what's going on.
Best wishes,