Are you using Steemit's WebSockets URL wss://steemit.com/wspa? If so, you need to switch it to wss://steemd.steemit.com.
I first noticed this when I saw one of my web apps that used this connection stop retrieving data. Later, @fabien had also posted this in the #dev Steemit chat channel.
If you have been using eSteem by @good-karma, you might see nothing loading. It seems changing the Server field in the Settings page does not stick. Upon changing it and hitting Save Changes, the page refreshes with the original value. One way to get around this is to change the Chain to Golos and back to Steem, after which the Server will end up wss://node.steem.ws. But, you must login again.
While https://steemit.com/wspa does respond with a HTTP 301 Moved Permanently to https://steemd.steemit.com, WebSockets clients don't reconnect with the resulting location.
To witnesses and developers with scripts and web apps, make sure you update your node connection. This includes Steemit.com clones, voting bots, witness failover scripts, price feed scripts, and connections to cli_wallet and piston.
I have updated my post List of Public Steem Full API Nodes, and Example Usage as well.
bitcoiner!