The NatVis visualizer allows many custom Unreal types to be displayed in a helpful manner inside the Visual Studio watch window. One such type is TSparseArray. Under normal circumstances, visualizing a TSparseArray behaved like viewing a standard array. This is not the case if the TSparseArray is not using the default allocator, which is unexpected.
1. Create a new C++ project.
2. Add a new C++ class, such as one derived from AGameModeBase.
3. Add a function that will be called by the engine, such as InitGameState().
4. Assign the game mode in the project settings so that it is used at startup.
5. Inside the function, add a variable of type TSparseArray<int, TInlineSparseArrayAllocator<16>>
6. Add several integers to the sparse array.
7. Place a breakpoint at the end of the function, compile, and run the code.
8. Notice that in the variable watch window only raw data about the sparse array type is displayed.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-352770 in the post.
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| Component | UE - Graphics Features |
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| Affects Versions | 5.6 |
| Created | Nov 6, 2025 |
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| Updated | Nov 10, 2025 |