Dynamic terms on a CPT with custom taxonomy

I have a CPT and a custom taxonomy. I’ve created a new post, added a section with a title inside. When I set the title to Dynamic and pick Post Title, for instance, it works great.
But when I pick Post Terms it won’t work, although the correct taxonomy is active.

Now, the strange thing is, if I add another taxonomy to the CPT and pick any of the two, it works fine! It looks like the taxonomy select box is not assuming the selected option when there’s only one taxonomy.

Has anyone experienced this? Is this a bug or am I doing something wrong?