When an address is being geocoded to convert to latitude and longitude, many UK addresses fail when the Post Code is provided, so Pro maps will try a second time without the Post Code.
It looks like the address neilo used is geocoding correctly. The difference is he did not use "Greater Manchester" for the state.
Try entering the address without the state:
Street: Wilton Street
City: Manchester
State:
Post Code: M34 3WH
Country: United Kingdom