Steve, I’ve tryed this and no success, same issues. To make sure, all plug-ins were also stopped and the theme was changed. By mobile access everything works fine. Unusual the post editor blank without toolbars too. I don’t know what else trying…
Thank you Esmi. I did this, copyed to notepad, saved as RTF format, cleaned all formating at the posting area, deleted any format in the text mode view. I realized this happened after wordpress upgrade. It also happens after more than 500 words. It seems like It has a kind of characters limit truncating the rest of the text inserted.