Excel Autofilter function not filtering all rows

I can't remember which template I'd used off the Office Online site, but had an issue whereby I couldn't autofilter the additional rows I'd entered. It was strange, I'd only added about 50 new rows, but they just weren't showing up in the autofilter drop down list. It was if the autofilter function was filtering by a set range.

Indeed it was. You can see the autofilter range at any time by pressing CTRL+G and then manually entering sheet1!_filterdatabase into the dialogue box.

To resolve the issue, turn off autofilter first and then select the new area you want to be included in the autofilter. Then re-enable autofilter and the new rows should now be included!