RE: Custom Entity in Custom Channel Tile
Hi Martin,
The issue might be caused by LookupViewId and QuickViewFormId properties are not defined properly in xml file.
According to sample xml file of documentation, althought the comment said that those two properties are optional,

however, from my test, they shall be populated;
I didn't add them in the first test, then I also encountered same issue(Stuck in Loading...) as screenshot you posted.
1. Open the lookup view of custom entity, then open console and use decodeURIComponent(location.href); function to get decoded id value of lookup view id.

2. Similarly, get id value of quick view form with same function.

3. Add those values to xml web resource of custom channel
Result:
Now records list for custom entity has been available:

test custom tile

Regards,
Clofly