3D tile dataset won't show up from URI


I am trying to load a 3D tile dataset from a third party API, but it won’t show up in unreal even though no errors or warnings are printed.

When using cesium ion’s API, the models show up. The only difference between the two datasets that I can see is the file endings of the content URIs within the dataset (see image below for the failing dataset from the third party API). Does cesium for unreal only support .b3dm file endings within a 3D tile dataset?