Adding credits for both "small wood blocks" and "large wood blocks" for the same person for the same track, I can add wood block twice, and add the specific "small ..." / "large ..." to each, but when I click done, the results aren't what you expect. Both instrument entries are added, and the last "as credited" still is applied, but the first one just has the default, and loses the specificity.

I've checked, and as a workaround, I can add that "as credited" bit back in by editing that line after the fact; both entries do show once the edits are finally submitted.