This matches an independently preserved case almost exactly. I have a historical ordinary-Chat GPT-5.6 Thinking/Extended turn at 102m26s, while current genuine GPT-5.6 ordinary-Chat turns repeatedly cluster around 25–26m with unfinished work.
OpenAI Support Case #13832863 contains the native historical/current request and turn IDs. The evidence thread is here:
If you are willing, please report your own example through normal OpenAI Support. If they give you a numeric Case Number, posting only that number here or in the thread above would let OpenAI correlate two independently affected accounts. Please keep request IDs, account details, HARs and private chat contents inside Support.