MarketPress Product page 404

I have MarketPress installed on a Multi Site network. Everything seems to be working fine except for the Products page. Visiting the store/products page delivers a 404 (page not found) on every sub-site I have attempted it on.

All the other default pages created by MarketPress work just fine.

Yes, I have saved the Settings/Presentation page a couple of times, but it appears to make no difference.

Pretty permalinks are enabled.

Anybody else come across something like this?