Steemit has been rather annoying recently, that definitely not helped by the otherwise awesome Steemit More Info Chrome extension. Although problems also occur without the plugin.
Nowadays I use Steemitstage.com, which is the official Beta test site for Steemit (yet one should only use their posting key, just because that's best practice). Steemitstage seems slightly more reliable, but I still write all my content in an offline/cross-device Markdown editor just to be safe. You could also check our hackmd if you prefer an online, super slimline Markdown editor, with excellent autosave and even collaboration features.