Workflow breaks Hierarchical Select

Sometimes, after taxonomy changes or workflow changes (I'm not sure how I can reproduce the bug for now) when I try to use hs_taxonomy selector on my node edit form, I get "invalid response from server". After exploring response code I realized that hs gets selectbox data not from taxonomy selectbox, but from workflow elements (that's a radio buttons with workflow states available). If I go to admin/build/workflow, disable workflow for this content type, refresh form, the problem is gone. When I enable workflow again, I don't see any problems, too. But then, may be on taxonomy vocabulary settings save, the problem returns.