You are using Stability and prompting using non-supported language.
It happends when Stability API is there, but a persona doesn’t have Dall-E tool.
Well, so it happened for me. Here is a support request for that, but I kind of solved it out by myself. But that behaviour changed some days ago. Earlier it worked even an user prompt was in non-english and back then I could prompt using Dall-E requests as size etc. without using Dall-E as a tool.
So… it still can be a bug. Or feature.