Creative Cloud Express/Spark change the position and size of some slides when exporting the file

So, lately I noticed that when I export my file, some of the slides comes off uncentered, zoomed in or at times horribly deformed. Yet, when I check into the project file, everything looks fine, even if I press preview there are no signs of the aforementioned bugs. Only way to fix it is to reupload the image in the affected slide slot.

Does anyone know what triggers this problem exactly and how to fix it in the first place?

Thanks in advance!