Which Umbraco version are you using?

15.3.0 and 16.0.0

Bug summary

While trying to create a template under another template, it is not saved properly and is not inherited from the template it was created under, as it should.

Please see the attached video, where in this case I am trying to create a test template/child template under a master template, but when trying to save the child template after creating it, the master template is somehow removed and am also prompted with a modal asking "Are you sure you want to navigate away from this page? You have unsaved changes". So of course in this case I want to make sure to stay and save again so my child template is created, but then the master template is removed.

I have tested this on v 15.3.0 and 16.0.0 and this issue happens on both versions.

Specifics

No response

Steps to reproduce

1. Go to a master template in the settings section
2. Under the master template create a child template
3. Try to save it and see that once you try to save the master template is removed.
4. Then click on another template and see that you are asked "_Are you sure you want to navigate away from this page? You have unsaved changes". If you click "stay" and save, then move away from the page, then the template you have created will be saved outside of the template you have created.

Expected result / actual result

once you try to create a child template from under a master template, the child template is saved correctly and shows under the master template.