I find it usually doesnt work as advertised and you have to find the "Advanced mode" button (a strong candidate for the worst piece of UI ever) and then fiddle with several properties.
Here's probably the best reference:
https://web.archive.org/web/20160314083037/http://blogs.msdn.com/b/robertbruckner/archive/2008/10/13/repeat-header-and-visible-fixed-header-table.aspx
The key steps from that blog past are:
You selected "Repeat header rows on each page" or "Keep header rows visible while scrolling" in the tablix properties dialog, but it doesn't seem to work as expected? You might want to try the following four steps if you are using a "table"-style layout:
- in the grouping pane, click on the small triangle and select "Advanced Mode" to show static members:

Grouping pane in advanced mode
verify that you have the properties grid turned on (in BI Development Studio use F4, in Report Builder go to the "View" tab and select "Properties")
select the corresponding (static) item in the row group hierarchy
in the properties grid:
- set KeepWithGroup to After
- set RepeatOnNewPage to true for repeating headers
- set FixedData to true for keeping headers visible
I edited this answer in Oct-2025 to link to an archive of the original blog post, and copy out it's key content