I've been using Gmail since 2005.

Up until a few months ago, when I would reply to an email, I would see my reply (with the "message sent" notification) immediately under the original email.

Lately (past few months) it's been hit and miss. I do see the "message sent" notification, but my reply does NOT always appear under the original email message. Sometimes it shows "threaded" and sometimes not.

When it does not, I feel I have to look at my sent folder to be sure that it actually went out.

So what's up with this hit and miss "threaded" view of the emails? I've googled it every which way but loose but am not finding a definitive answer.

Bueller? Bueller? NeedKarma?. Scott?. Ben?. Anyone... Anyone... Bueller? :)