If you share a sparsebundle using dropbox (by the instructions in help), then at some point tell espionage to "Decrypt folder" on one end, the sparsebundle is deleted from dropbox (correct action). However, if you then go to the other machine, Espionage complains that it can not find the sparsebundle. There appears to be no way to recover. I can attempt to "Force remove from database", but Espionage prompts for a location to "save" the sparsebundle, which will fail when it can't be found.
Thanks for letting us know sjf_control, we'll look into fixing this issue for the next update so that "Force remove from database" actually works.