The forum software for some time has had an auto-save feature when you are making a post. I think some people might have been thrown by the periodic delay while the contents of the currently being written post are automatically saved.
While I am writing this post, after a minute or two, the bottom of the text entry box shows a message "Last auto saved: 5:45:39 pm"...when the auto-save occurs, there is a slight delay and you might get an indication that the text entry is busy (something like those stars or whatever that appear at the top of the screen), probably depending on the length of the post and your connection speed.
So, why is there an auto-save? It appears to be every 2 minutes...your post contents are saved in a temporary holding area in case you have to refresh your page.
If you do a refresh of that page, you'll see you appear to have lost everything you typed in...but you haven't!
Click in the text entry box and you will see at the bottom of the box "View auto-saved content". Click on that message, and a box containing the post contents as of the last time it was auto-saved will appear. You can click on the button that says RESTORE CONTENT, and you're back in business with your post.
I am including some screen shots to show this sequence.