So the one issue that comes to my mind is that you are starting to use the editor before it's completely loaded, which takes some time, probably around a second, give or take ( editors are built with lots of magic and it takes time to load 'em up ). And the truth is, there are not many ways to go around, maybe blocking the whole editor until it's loaded to prevent confusion but that's also not the nicest of solutions. Anyway, could you please let me know if that's actually the issue or it happens after the editor has been loaded anyway?
It happens if I use the options in a thread, especially the "Quote" option, post to the thread and then scroll up to that page to respond to another post, sometimes it works and sometimes it doesn't, more often doesn't. So, it would appear that once a post is made, you have to leave that page and come back to it in order for the options to work again.
It happens brutally often, if I didn't know some tricks I would have missed debate deadlines due to it. It takes many, many refreshes to fix and even then sometimes you need to go incognito and refresh 10 times or reload the entire incognito page free of cookies and cache to make it work.One thing I found increases the odds of success is clicking the text box immediately after the page loads but NOT TYPING immediately.
