Last night I noticed a bug while moving islands.
After conquering the Hydra islands, and having them retaken by opponents, Imwas bring Promethus over to help protect them. I was checking the defenses of the first 2 islands when I noticed the error. Going from the 3 islands (gold) next to Medusa islands it was going to cost 224 ambrosia, but if he attacked the second island from there it would only cost 121 ambrosia.
I have pictures but they are too large to upload.