I figured out why some of the comments have either disappeared, or not posted.
Blogger added a new feature that is supposed to filter spam comments posted to blogs. It was their attempt to filter out the Asian porn comments that were being spammed across blogger:
"Blogger now filters comments that are likely spam comments to a Spam Inbox, much like the spam folder in your email. When someone leaves a comment on your blog, it will be reviewed against our spam detector, and comments that are identified as possible spam will be sent to your blog’s Spam Inbox, found at Comments Spam. "
As far as I can tell, it can't be turned off. I have all the missing comments in my blogger comment box, a feature I didn't even know I had.
Until this bug gets worked out, when posting your comment, take a look at it and ask yourself if anything in it would look like spam to a filter. If you leave an http link or URL without it being formatted as a hyper link, that may trigger it. If you misspell a word for dramatic effect, like "whaaaaaat", that might do it as well.
I'm going to empty the spam box, and check it every day. Sorry for the trouble. The only other option would be to moderate all the comments by having them reviewed before posting, which is not something I plan on doing.
I restored many of the missing comments. I don't check the blogger settings often, and it looks like none of you do either! I assume some of you are having the same problem on your own blogs. Well, I solved your problem. No charge.
If you post a comment and it vanishes, here's what you should do. Re-post it, but try and change it to bypass the spam filter. For instance: don't use all caps, spell words as correctly as possible, avoid http links that are unformatted. If this doesn't work, I'll be checking the Blogger spam box each day. Hopefully, by marking certain users comments as "not spam" Blogger adds you to a safe list.
Sorry for the inconvenience. On the other hand, if Blogger ever adds a feature that allows me to block certain commenters, watch out.