IsAllowedEntity endpoint broken in 7.13.2

[lars-erik]

From our: https://our.umbraco.org/packages/backoffice-extensions/umbraco-relation-editor/general/95842-adding-relations-between-child-list-items

Possible dupe of #11, #19, #20, #21

---

Hello!
I have installed the version 1.2.3 of the Umbraco.RelationEditor on Umbraco version 7.13.2.
I am trying to add a relation between a content item in this tree Home/Persons/Person to another content item in a Home2/Persons/Person. (it is a copy to serve as another language). When I select / search the Person by name and click ok I get the error: × Request error: The URL returned a 404 (not found): /umbraco/backoffice/relationseditor/relations/isallowedentity
I have also reinstalled the package but no luck. Otherwise it works fine for content that is not an item in a list.
Any ideas?
Thank you! Cosmin