Hi, Thanks for contacting us! We haven’t removed any features, but jigsaw collages are currently limited in that the Rows and Columns sliders (down the bottom left when creating a collage) are disabled for this type of collage. You can adjust the Proportions slider, however there isn’t currently a way to adjust the proportions of a single cell within a collage.
We will be looking at further enhancing collage in the future, to let you remove and change the proportions of an individual cell. Let us know if you have any further questions!