An Xpath on the datasource should not affect the editability of the datagrid column.
However; if the security access rule has an Xpath which allows the user to edit a certain set of data of that entity and the Xpath on the datagrid matches that XPath, then only the objects with no write access are displayed and thus making the column not editable. ;-)
Thanks for giving such a quick reply. I looked security settings and all seem fine. However I forgot to mention that my datasource is xpath that goes over an association. Perhaps the fact that I go over an association is the problem?
To be complete: this is the error I get in the console:
An error occurred in listener of event 'onCellClicked': TypeError: Failed to execute 'appendChild' on 'Node': parameter 1 is not of type 'Node'.