If there are some out there migrating from Things 3 (like I did) to OmniFocus 4, then you should be able to use the following Apple Shortcut to migrate your data.
- Select the items to migrate in Things 3 (Projects, Tasks)
- Run the provided Apple Shortcut
Result: A new folder called „Things 3 Migration“ gets created for migrated projects. Single actions get created in Inbox.
There has been a longer discussion about this topic before. This post is just to make finding the final Shortcut easier.