Yes, I noticed that when I typed another character it would catch up. Still weird that this is the behavior, because if a space is counted as a character, then it should be visible, otherwise if it shows 13 and the limit is 15, that means I have 2 more characters, but then it jumps from 13 to 15 (in my case it will hide the count). All because there’s a space at the end. It can be a bit confusing for the users.
But if it’s something you can’t change, then I guess “it is what it is” 
This is already a useful tool, regardless. 
Thanks