BUG: `.;` doesn't work to replace an inner-most value in a multi-dimensional list (i.e. matrix)

[kcruijss]

Although replacing inner-most items with : or .: works fine inside multi-dimensional lists, with .; it doesn't do anything and results in the multi-dimensional list unmodified.

Try it online to reproduce.
Came across it in this codegolf answer of mine.