When upgrading Nokia N97 from a previous version to v20.x.019 with Nokia Software Updater, the scrolling in the Ovi Store client may not work properly after the upgrade. The issue occurs only when upgrading to version 20.x.019, not when upgrading to newer phone software versions.
The problem can be fixed by installing a new Ovi Store client via the Download! application. Select Menu > Applications > Download! and install the new Ovi Store client.