It has always been true that when you are editing a comment the replies are hidden.
Probably the disappearing edit button is that it is not available on one’s user page. But it is available on post and permalink pages.
Edit: I, too, had a glitch. I went to recent comments and I had two comments visible. This one had an edit button and the other didn’t. A reload fixed it. The one that didn’t also lacked a reply button, fixed by the same reload. Since only my comments have edit buttons, but all comments have reply buttons, there are more opportunities to observe reply glitches. After the reload my comments were fine, but this comment lacked a reply button. Another reload fixed that.
My comments don’t have the button for editing them any more. Have other people’s edit buttons disappeared?
No, I still have edit buttons.
My edit buttons seem fine.
My edit button has reappeared, but if I use it, the replies to that comment disappear temporarily, so this is looking like a random glitch.
Edited to add: The reply didn’t disappear, so random glitch.
It has always been true that when you are editing a comment the replies are hidden.
Probably the disappearing edit button is that it is not available on one’s user page. But it is available on post and permalink pages.
Edit: I, too, had a glitch. I went to recent comments and I had two comments visible. This one had an edit button and the other didn’t. A reload fixed it. The one that didn’t also lacked a reply button, fixed by the same reload. Since only my comments have edit buttons, but all comments have reply buttons, there are more opportunities to observe reply glitches. After the reload my comments were fine, but this comment lacked a reply button. Another reload fixed that.
Me too.