This function is the problem:

AcquireSRWLockExclusive is one of the functions utilizing this compatibility layer. However, most custom allocators indirectly rely on this function.

This means that allocators must be re-entrant, which is essentially impossible since re-entrancy detection requires thread-local storage, which in turn calls AcquireSRWLockExclusive.

For some reason I haven't been able to fathom, this does not always result in a crash, so many custom allocators which rely on TLS appear to work. However, seemingly inconsequential changes (such as changing the size of a struct) result in the program crashing with an access violation or stack overflow.

The fix is to remove this allocation and encode these strings at compile-time.