On My MacBook Air, using Messages, there is a single text chain which will not allow me to respond (i.e., there is no text prompt to type within). A few notes:
All of my other macOS and iOS devices allow me to participate in this text chain. That includes my MacStudio, my iPhone, and my iPad...
I want to do a clean install of Monterey from Big Sur but I also want to migrate some data rather than starting from scratch. The data that I want to migrate are:
Safari history.
iMessages.
Music (especially play count for tracks).
That's all. Everything else can start from scratch.