Haunted Spooks production dates question

[Robert Moulton]

Richard's amazing new book lists production dates for Haunted Spooks as being Jan 05-17 and Feb 09, 1920. I thought the understanding was that the bomb incident where Harold lost his fingers occurred during production of this film and that that could be verified by the fact of seeing Harold with and without the prosthetic in the film.

Do the 1920 dates only, with no 1919 production dates, simply mean the 1919 production dates are not known at this time? Or is there a more complicated story here?