Answer
Among the several similarly-named B2B-related projections, there can be one specific, easy-to-overlook projection tied to that exact action (like configuration) that isn't covered by granting the more obviously-named B2B screens — if a permission error persists in B2B despite all the visible B2B screens being granted, check for an additional, less obviously-named projection specifically backing that action rather than assuming the broader B2B grants are automatically sufficient.