Why is Guided Access not functioning on my iPhone?

Over the last year, across about 6 different Apple devices (iPhones, iPads), and the same number of iOS updates in that time, Guided Access no longer works. I know how to use this and have for YEARS. I know the settings. Yet triple click does nothing anymore. Tech “experts” have us toggling on and off, powering phone on and off, updating software but simply put, Apple appears to not be supporting Guided Access. Does anyone have a significant intel on this?

[Re-Titled by Moderator]