testing v2.52a2 on win7 pro 64

I'm finding some posts don't seem to work. It appears that in some cases it is the size of the post.  I was able to post 20k and perhaps a little higher. I have been trying to determine the limit which when exceeded causes a yellow "!" triangle to appear. But I am finding that at times even posts under 10k won't work.

I am curious about the inconsistency. Is there a fixed post size limit? If so, what is it?

What could cause a small(er) post to fail when ones nearly 2 times as big successfully send?

When they fail, it appears some excess encrypted text displays in the Share tab, without the ##msg: header (unless the edit view is active)