C# Virtual list view not checking items that are not visible in GUI

Question

Hi all,

I have a virtual list view and each row has a checkbox, I have a master checkbox that checks all the rows in the grid, this works fine until I filter some of the rows (all rows currently unchecked) and then load back all rows into the list view and then click my master checkbox to select all rows, all rows appear selected until I scroll down and then the rows I filtered are not selected but the rest are. Now this sounds like an obvious bug but if I make my window bigger so I can see at least one of the rows that was filtered and then click the master checkbox the visible row is now checked in other words rows that are not on screen that were previously filtered remain unchecked.

Any ideas why this would be?

Thanks