Select Multiple Error - Layout abandon and instead overlap of check pots and choices

Hello everyone,
I am new to qualtrics and have been working on a quite long survey, which is done now, however with a major problem. That is, in multiple choice questions with Select Multiple the displayed question in preview does not follow the chosen layout (Modern/classic) in which the text is written inside the box, and instead shows the choices and check pots overlap which overlap as in the picture below. I know I can partly solve the overlap with Rich content editor (however then only either in the desktop OR mobile version), but this will not solve the layout problem... Note, when starting a new project, the issue is gone.
To provide all information even though I do not think, this would have to do something with this problem: I had created the survey from a copy, in which I merely changed one thing in the qsf file in order to be able to use "edit multiple". I did so by following this, which worked perfectly fine, and I did not think it could be the reason for my problem, but I am mentioning it here to provide the full information.
https://www.qualtrics.com/community/discussion/1297/a-workaround-for-the-disappearing-edit-multipleAll help will be much appreciated!! I hope I will not have to redo the entire survey in a blank project :(