I ran into this recently as well. It has to do with the number of DLLs allowed by windows when attaching a debugger to a process, which is capped at 500. It seems that UE5 has many more DLLs than previous versions so it’s hitting that cap, and depending on the order in which the DLLs are loaded, it will cause some to not show up in the list (you can view the loaded modules when attaching a debugger by going to Debug->Windows->Modules in Visual Studio). The solution to this issue is actually in this other thread, but it involves changing a registry key to increase the max number of DLLs. Hopefully this solves the issue for you as well.
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