Now I see
You need to a capture portion
I use REGEX mode (the saved search in my Example, did not have it set)
The original was: TheSeries 1 - title
There are 3 sets of captures (this one is for Title portion Only)
DO the Source field (Title) LAST as that replace deletes the other field values
Title is the 3rd capture, thus the \3
If you were populating Series, the destination would be Series and the value \1
then you populate the Series Index and the replace value is \2

I never could get Series to work as a single step
Does this help get you going?