Some corresponding icons to the ones shipped with fedora-logos don't exist in generic-logos, for example hicolor/*/apps/fedora-logo-icon.* hicolor/*/places/start-here.* are missing in comparison to fedora-logos. A full list of missing files / icons can easily be obtained by running rpmdiff.
generic-logos-18.0.0-3.fc26 has been submitted as an update to Fedora 26. https://bodhi.fedoraproject.org/updates/FEDORA-2017-f4e46d314c
generic-logos-18.0.0-3.fc26 has been pushed to the Fedora 26 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2017-f4e46d314c
generic-logos-18.0.0-3.fc26 has been pushed to the Fedora 26 stable repository. If problems still persist, please make note of it in this bug report.