Hi again,
Yes, It happened with me too that my whole comment lost after I pressed the POST button. It's very frustrating!
I don't think however that this is a blockchain problem. I believe it more likely caused by the increased traffic of the Steemit platform (the site itself) and the fact that there is 288,000 page views every day. Which puts hard pressure on the Steemit servers.
As I saw many people complaining about these kind of glitches, I'm sure that the developers are aware of the situation and they will do something about it if they can.
We just have to be patient and don't let a glitch ruin our day, even if you have to write your whole post all over again:/