... they're just hiding.
In the latest Tap Forms Mac 1.1 update, when you launch the app after upgrading, it may appear that your forms have disappeared and you're only left with your categories. That's not the case. The category headings are just collapsed by default. Just hover over the category names and you should see a Show button to the right of the category name. Click on it to expand the category to reveal your forms as they were. If you don't see the show/hide link, then simply resize the left panel to the right and you should see them.
Sorry for the confusion.
Thanks,
Brendan