I have two columns in Workbook 1 - "Issues" and "Regions" as below:

Issues Regions
1111 Eastern
2222 Atlantic
3333 Eastern
5555 Midwestern
6666 Eastern
7777 Midwestern

I'm trying to create the filtered results in the Second Workbook or file, with the same two columns, as below:

Regions Issues
Atlantic 2222
Eastern 1111, 3333, 6666
Midwestern 5555, 7777

Could you help me with a formula to achieve this? Thanks!