LinkedButton in Matrix (v. 6.7) and disappearing rows

We just tried adding a LinkedButton column to a matrix as per the sample instructions:

Dim oLink As SAPbouiCOM.LinkedButton

Set oColumn = oColumns.Add("A", it_LINKED_BUTTON)

Set oLink = oColumn.ExtendedObject

oLink.LinkedObject = lf_BusinessPartner

The link works, however, our matrix is on a tab (or pane level) and when the tab is changed and subsequently changed back, the data in the matrix disappears.

When we take the linkedButton out, the data in the matrix does NOT disappear when we change tab pages.

Is this a known problem?