Bugfix: The FSS Read process at should only process if index_at is non-zero.

Bugfix: The FSS Read process at should only process if index_at is non-zero.

The FSS Embedded Read recursive logic exposes this problem.

The at flag bit is set when the at parameter is passed.
The at parameter being passed when there are multiple depths does not mean that the specific depth in question should be using the at position.
Add a check that ensures that the current depth needs the at position processed.