Odd and annoying behavior on snippets (all layer moves not only the photo)

Good afternoon to all. I’m quite new to the Fotomagico Software, there’s one thing I do not understand.
When I select a default split screen and drag into the storyboard then I drag two photos in the place holders and thats fine. The problem is that sometimes I cannot move the photo in the mask to center it because the whole layer moves (not only the photo inside the placeholder). Sometimes it works fine and sometimes not without me changing any parameter at all. Can you please advise if I’m doing something wrong or it is a bug. Waiting for an answer cause I’m currently stucked in my workflow. Thanks to anyone who can help.