Can't Update when Linked (1 Viewer)

I am working in FrontEnd1

Linked to two databases:

My Data is in DATA1

My Reference Data is in DATA2

When I create my Query (one to many) in FrontEnd1 I am unable to update DATA1

If I move DATA2 into DATA1 then my query works.

Is there something I'm doing wrong here?

some tables will not allow this due to the relationships.
check yours to see if it will allow.