I've been having the same problem. Many folks say their frogs go in the water, but my frog seems to hate being put in the water. He only wants to sit in it if he chooses it. I spent a day giving him a total of 3 honey baths, each time bathing him until the water got too cool. He still never relieved himself, but he doesn't have a hard lump and still eats happily, so I think he may be one of those who prefers to go in his substrate?

Anyhow, I'm playing the same detective game as you, so please keep us updated on how this turns out and what you discover. I think