When making a split on a lengthy project it would be normal to expand the timeline horizontally. Otherwise, the split wouldn't take place at the intended spot. 
Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. From the HOME tab, that choice is available by clicking the caret to the right of the Save Project button on the toolbar. Then you're protected.
Backing up the project and sharing, as instructed above, won't mess up the project, but will let others test the issue you are having.
Knowing what release was used earlier isn't important. If it was purchased, your receipt will likely list it. You can try old versions by downloaded from the site that Dangerfreak linked above. Ignore any virus warnings.