Tried photo masking the Bronze Age axe today and I am having some trouble.
First of all, at some point during my outlining, the program closes the polygon on its own while I am not finished yet with outlining. So I get this weird-shaped polygon that half-follows the object and then just cuts off at a straight angle to connect to the point I started out with.
Second, the editing option does not seem to work for me. Re previously described situation, I tried to edit my polygon after it closed on me, because I was nearly done and just needed some fixing to finish. Turns out I can click on edit, within the polygon or on the line as much as I want to, but the polygon stays yellow and does not turn blue again so I can edit the points.
Without the ability to edit the weird-shaped polygon that I did not create, I deleted the polygon and started over. To my frustration, the same thing happened again and I still was not able to edit. So I gave up for the day and figured I should report the issue here.
Hope someone can help or at least that this information is useful!