Error when opening Hierarchy view of account entity in model-driven app

Hello everyone

I have made a model-driven app that shows the Account entity. By default, the account entity has a parent-child relationship with itself.

When I click the Hierarchy view, I get an error:

When I check for more details, I get the following:

When I see the error, I can see that an undefined object is trying to do the '.ToLowercase' method.
But when I check my typescript/javascript, nowhere does it try to do a 'toLowercase'.
I see that the error does mention the sitemap or the sitemappanelactioninspector, but I don't know how I can debug this or find out where the error actually lies.

I don't have any scripts running for the hierarchy views, or any plugins on the account entity.

Any help would be much appreciated.

Thanks!