If you have an issue with a Scribus file, it's very likely that it can be solved by looking with a text editor at its content.
But there is no way to tell you what the problem is, without having a look at the file itself.
If you can share the .sla file, you should upload to a file sharing platform and put a link to in the question.
An alternative is to open a ticket on https://bugs.scribus.net and upload there your file. If you mark the ticket as private, only the developers will be able to see your file.
I don't think that Statckoverflow has a way to share private messages with other users, so you cannot directly find a way to send me the file... but if should not be that hard to find one of my email addresses if you look for my name and Scribus.