Lousy that it's happening to others here, too.
Here is what it looks like after posting, for those who haven't seen this symptom ... my post remains in the edit box after clicking "Post Reply" but nothing is refreshed in the topic:
You need to manually refresh that page to see if it posted correctly.
So the next time I come back into the refreshed topic, that prior post text is
still in the post edit box when just browsing. You can only remove it by posting again and hoping it works that time, otherwise it stays in there until you post successfully: