In light of the forthcoming M2.8 I am in the process of clearing the decks for that release, so please find here the last (almost certainly) release of the Grid format for M2.6: https://moodle.org/plugins/pluginversion.php?id=7113.
1. Fixed CONTRIB-5256. Thanks to Marius Jugariu for reporting the problem. 2. Fixed CONTRIB-5260. Thanks to Dan Jeffries for reporting the problem.