I have been to the treasure point and dug for treasure. Guybrush some how had a shovel there and seemed to stick it in his pocket, but when the dog led him to Caleb, the shovel was not in the inventory. Cannot dig up the treasure even though I think it is beneath Caleb.
Also, altho I bought a picture from Claeb, I don't remember him ever taking one.
I am playing the PC version.