@Mark Drake I've just googled your issue and found(https://stackoverflow.com/questions/37442817/npoco-one-to-many-and-many-to-many) from the syntax in the question I think you might need to make your

List<int>

-->

List<ContentTypeDto>

and

List<NodeDto>

and remove the

ForeignKey(typeof...)

attribute. In the forum post you linked I think the issue there might be

[Reference(ReferenceType.Many, ColumnName = "TournamentsId", ReferenceMemberName = "TournamentsId")]

where the

ReferenceMemberName

set doesn't match the

Id

property on the referenced table but instead have

TournamentsId

specified. (*It's a wild shot in the dark I haven't worked much with NPoco * 😅 )