Setting leverage to none should be okay first of all but access to other currency pairs would be helpful.
I only can take the minimum sizes Kraken has set but these are original your settings in the Zorro.ini section, I can't see any error there.
Do you think there is a difference if a fiat currency is used? I guess they are treated the same way as cryptos.
Maybe any other user has an idea, I fear my possibilities to debug are very limited at this point.