Report X needs to list records in Form A that includes fields from Form B (ideally as additional rows)

Creator shows "-No Value-" for any/all of the fields coming from Form B.

I'm assuming this is because reports support forms related by a multi-lookup, ie 1-to-many relationship ?

In the example image uploaded the fields System, Sub system and components are on Form A while Mitigation Task Type and Summary come from the looked up Form B.

Hoping I've missed something obvious!