Document edit via WebDAV sets workflow into undefined state

[nsilent22]

Plugin version: v4.1.2.

Steps to reproduce:

1. Upload a document into DMSF.
2. Create workflow.
3. Assign it to the document.
4. Start workflow.
5. Unlock document.
6. Edit using WebDAV.
7. Workflow state changes to 'Waiting for Approval'
8. While clicked it displays a table with only three rows (steps from the workflow are gone), stating: None, Assigned, Waiting for Approval in the 'Workflow' column.
9. No one can do anything with the workflow now.
10. You can 'reset' the document workflow by creating new revision (Edit -> [+] -> Create).