Are you sure it is the right thread? On mine it shows the title of the last agent thread even though I'm in a text thread.
I opened a previous agent thread and it gave me the option to include both threads to the context of the inline prompt (the old text thread was included and I had to click to exclude it, the new thread was grayed out and I had to click to include it).
edit: yup, they fixed it 2 days ago