Several things:
Why do you import the number at all? A mask
%dummy%. %artist%
would only use the string after the dot.
To get rid of the number you can either use an action of the type "Format value" and as format string $mid(%fieldname%,4,$len(%fieldname%))
or an action of the type "replace with regular expression"
Search string: "^\d+. "
(leave out the inverted commas - they should just show you that there is a blank after the dot)
Replace string:
(leave empty)
The $mid-function lets you address more or less any position in a string.