PRODUCT ACTIVITY STOPPED RECORDING ON SOME PRODUCTS

When I open a product in the 'Products and services' tab, the product details screen shows the correct last order date and quantity but in this doesn't match with the most recent GO/GI in the 'Activity tab' which seems to have stopped recording GI/GO.   If I run a product activity report, the more recent activity does not show either.  It's not happening on all products and I can't find a common theme.  Has anyone else come across this or know of a fix?  At present, when a I need product activity information I'm pulling a 'Purchase Orders By Product' report and all of the activity shows, so I'm not sure why the same information isn't carrying across to the product activity screen/reports.