Can't link a backend to my Static Web App preview environment

[sebastianblesgen]

Describe the bug

As explained here it's not possible right now to link any API to my preview environment. Error says "An error has occurred" even before I click on Link. Clicking does not help.

To Reproduce
Steps to reproduce the behavior:

1. Deploy a Static App on a non-production environment
2. On API menu, click on the related link
3. Select Web App and other required values from drop-down list
4. See screenshot the error

Note: It's apparently the same for Functions

Expected behavior
Well, I don't expect an error message and instead have my static app linked to the backend API

Screenshots
See above and here trying with az CLI