Get SSRS Tablix headers to repeat on each page

This approach worked for me (from https://stackoverflow.com/questions/11285923/tablix-repeat-header-rows-on-each-page-not-working-report-builder-3-0):

1. Open Advanced Mode in the Groupings pane. (Click the arrow to the right of the Column Groups and select Advanced Mode.)
2. In the Row Groups area (not Column Groups), click on a Static group, which highlights the corresponding textbox in the tablix. Click through each Static group until it highlights the leftmost column header. This is generally the first Static group listed.
3. In the Properties window, set the RepeatOnNewPage property to True.
4. Make sure that the KeepWithGroup property is set to After.

The KeepWithGroup property specifies which group to which the static member needs to stick. If set to After then the static member sticks with the group after it, or below it, acting as a group header. If set to Before, then the static member sticks with the group before, or above it, acting as a group footer. If set to None, Reporting Services decides where to put the static member.