I got in the habit of writing "1 solo" years ago because of that very issue. It may look silly, but avoids the ambiguity nicely, and so far nobody's complained.

The new version is Finale 25.

Welcome news! http://www.finalemusic.com/blog/rewire-support-next-version-finale/

Can I just confirm that when you click and drag, you're clicking outside the staff, then dragging to a point inside the staff?

One of the most common mistakes made by new users is to confuse ties with slurs. I don't use Notepad, but I assume there is a tie command in simple entry just like there is in Finale. Use that.