This matches my experience as well, "adaptive thinking" chooses to not think when it should.
It was terrible. You could upload 30 pages of financial documents and it would decide "yeah this doesn't require reasoning." They improved it a lot but it still makes mistakes constantly.
I assume something similar is happening in this case.
I faced the same issue using Open Router's intelligent routing mechanism. It was terrible, but it had a tendency to prefer the most expensive model. So 98% of all queries ended up being the most expensive model, even for simple queries.
With a small bounded compute budget, you're going to sometimes make mistakes with your router/thinking switch. Same with speculative decoding, branch predictors etc.