Option to Publish Vanished Overnight

Yesterday I built three GPTs and didn’t publish them, although I could have because the options to publish to everyone, or anyone with a link, appeared when I clicked the “…” to the right of the GPT name. I have not edited these GPTs today, but the option to publish has disappeared. When I click “…” all I get is a red button “Delete GPT”. Is anyone else experiencing this issue?

I built a new GPT today, more complex than those I built yesterday. When I tried to publish it, that was when I realsed the option to publish has gone – not just from the new one today, but from all my GPTs. Could this new GPT be the cause of the issue?