I literally just did this a few moments ago. haha.

I said "maybe think for a while on ideas and then give me a few options? " and Opus 5 still just did the thing, while 4.8 gave me options. Same exact prompt and context.

I added a system prompt paragraph explaining that a question is just a question, whether or not I’m in plan mode.

It still just takes the question as a directive and jumps to action when I’m looking for clarification.