There doesn't appear to be anything wrong with your code. It would perhaps be easier to diagnose if we knew which line of your snippet was line 223?

That said, I generally create a single B::T object at the beginning of the program and the call report at the end. That allows me to time several portions of the code by using different tags.

I can't see how your use of close scoping would affect the outcome or produce the error you're seeing, but I thought I'd mention it anyway.

If you don't want to post the real code, then I think you will have to try and produce a small testcase that reproduces the behaviour before we can help you further.