Power Query Grouping undos sort

I have a table listing providers (Table "Cities") and the cities they serve. If a provider is in multiple cities, they would be listed each time but on a separate row.

2nd table (Table "Providers") isolates and displays only unduplicated providers.

I am attempting to produce a table of unduplicated providers with 1 merged column of all the cities they serve. Cities should be separated by a delimiter (comma) and displayed alphabetically.

Steps followed in Power Query:
"Cities" Table
1. Sort by Provider Name and then City name.
2. Group rows
3. Added Custom column to isolate distinct rows by delimiter.
4. Extract values of list
At this point the Cities are displayed correctly with delimiter and in alphabetic order.

As soon as I merge "Provider" query to "Cities" query, the contents of the "Cities" column are no longer in alphabetic order. I'm not sure why this is happening.......frustrated!