Hi,
Can you try the following steps?
1) use CRXDE Lite and check that these 150 XPs are still there
2) Check that you are using the same display mode/layout
3) in TouchUI check the request performed by the browser and find out how many XPs are returned.
4) Validate the changelog of the service pack 6.4.6 (and the ones you skipped) for any indication of a change