Whenever you add new transitions to your document you need to reimport your results in order to see chromatograms for the new things.
You can do that by going to:
Edit > Manage Results > Reimport
I do not understand your question about exporting a transition list and then getting an error when you try to import it again.
I might understand your question if I could see your Skyline document.
In Skyline, you can use the menu item:
File > Share
to create a .zip file containing your Skyline document and supporting files including extracted chromatograms.
If that .zip file is less than 50MB you can attach it to this support request.
Otherwise you can upload it here: