Unable to select target version in App Installer when set to Manual.

When you select Manual as the update method, the last version available from the Jamf App Catalog is applied to the deployment. When a new version is available, an information icon appears next to the version deployed on the summary view page that indicates the latest version. You can then click the Select version icon in the Action column to choose a newer version to apply to the deployment.

The selected version will remain in place on computers in your scope until you manually select a newer version or change the update method. This includes any new computers that are added to the scope.

After choosing Manual as the update method, you will have to wait for a new version to be released before you can select a version.