We’ve had a few bugs related to data migration, tabs and sharing/importing of tabs. All of these issues should now be resolved. We have now made it impossible to lose widgets by preventing tab deletions unless they are empty. We have run a script so that any widgets from any accidentally deleted tabs should now be restored. Please let us know if you are still experiencing any issues via our contact form here.
By the way, you can drag widgets to different tabs. An arrow will appear above any tab that you drag a widget to, as illustrated in the screenshot.
Also note that the default tab which will be selected when you load your Protopage will be the first tab in the first category in your Protopage. You can reorder tabs and categories simply by dragging and dropping them.