I think Im having same problem with u.
I m running workflow system and sde version.
I have created version (JTX step) by administrator and given privileges to the editor (EDITOR, GRANT, GRANT - feature class & EDITOR, GRANT, ASIS - attribute classes).
However, when editor use that version, he still can edit both spatial and non-spatial data.
I worked separately with arcmap and sde. the granting versions work well.
Maybe sde and privileges for version through WMX has some limitation or I miss some set up??? EMERGENCY HELP?