We need more details to troubleshoot your issue.
- What version of Unreal are you using? What version of Cesium for Unreal are you using?
- What dataset are you using? Is it from the Cesium ion Asset Depot, or is it your own data?
- What type of data is it – terrain? Photogrammetry?
- What is the expected behavior? Does it load correctly in CesiumJS? You can try it out in a Sandcastle.
The more details, the better 
my unreal version is 5.2.1 and cesium version is 5.2.0 …i am using my own dataset from url option (google earth by putting the api key step) …and in sandcastle demo…ur gallery option such as 3d tilesets were opening the way i wanted but if i searched my locality…it showed it like a 2d map which i have a complain about earlier
Unfortunately, there are areas of the world that the Google Maps Photorealistic 3D Tiles dataset doesn’t include 3D buildings for. You can confirm this if you go to the location in Google Maps itself.
There’s no solution other than to request that Google provide coverage for this city. You can do that with the “Send Feedback” page near the top right corner of this page.
so suppose if i want a famous area…say newyork city on my ue5 project…how can i have that???
Well, for any application, you need to actually have the data of the areas you want. Google Photorealistic 3D Tiles does contain New York City, which you can see in the Cesium for Unreal Samples.
What data are you really asking for?
in cesium samples…i am trying to open the melbourne map in another ue5 project…but it does not opens there is a big white screen…and if i try to go on third person mode…its does not happens