Answer
Check whether the view causing the error is a standard report view (one ending in _REP) or something else — IFS's Crystal Reports setup only automatically handles standard _REP-suffixed report views for the print-time database users (typically IFSPRINT and IFSSYS). If your report layout directly references a non-_REP view (like a base data view), that view needs explicit SELECT privilege granted to IFSPRINT and IFSSYS specifically, since those are the accounts Crystal Web Service actually uses at print time, not the account you tested with directly against the database.