Only last tag gets assigned after clicking "assign" button

[svenhabex]

When I select multiple tags in a tagfield and click the "assign" button only the last tag gets assigned. This issue is difficult to reproduce and only appears with specific tags.

Example:

After assign click:

Only the last tag gets assigned because in "assets/components/tagger/js/mgr/extras/tagger.tagfield.js" on line 273
this.store.find('tag', value) returns -1 for all tags except the last one.

There is nothing "special" about these tags that produce this issue. Can someone point me in the right direction why only the last tag gets assigned?