This is a strange one, and has been present for me for months, but didn't try to nail down what specifically was the issue until tonight.
I'm using the Chrome browser on both ChromeOS, Android, and FireOS or whatever the Kindle OS is. Problem followed to every device.
In the general settings, near the bottom, I always used the Enhanced Interface, Full WYSIWYG setting.
The following problem occurs when replying to a thread with a quote, when using the above setting. It doesn't happen in a regular reply, or new thread, or in the other interfaces.
The problem is that the spacebar will not work until I hit the [enter] key, then my spacebar is unloacked, so to speak. Say I'm replying to a thread about dogs and I quote someone and want to say that I want a dog. I hit [reply w/ quote] then start typing. when I hit the end of the sentence I notice it looks like the following.
"Isurewouldlikeadog."
I can go back and use the spacebar to add the spaces, but even if I keep writing, the spacebar will not make the next character a blank space until I hit the enter key. Then it will work as normal.
If I reply with quote and just hit the enter key once or twice before I start, the spacebar works as normal.
This problem does not occur in the basic or standard editors, just the Enhanced, but it occurs 100% of the time for me. Again, tho, only when replying with a quote.