I haven't tried this with AFR myself, but usually if you want to search/replace symbols like ? and *, you need to put a tilde (~) in front of them: ~* or ~?.
I don't know if this will work in a replacement but it certainly works when you are searching.
Just to let you know:
you should normally use search for *
and replace with desired char.
But we found some issue for replacing in MS Excel files (occurring
only in the latest version of the program). It will be fixed next week.