Taxonomy, add multiple new tags at once.

Hello!

We have a taxonomy "Taggar" (Tags in english). When we add a taxonomy field and allow creation of new tags using metabox, we can only add 1 new tag at a time, if we add 2, only 1 is left selected when closing the "new tag" box.

See the video for clearification: https://imgur.com/a/9rxG9FS

The tag is created, but not populated in the tag field, only the last added one is.

How can we solve this?

Here is our field data json: https://pastebin.com/FDfTkjEW

Thanks