A lot of people have mentioned the “close” issue – – it comes up with garage doors, also.
The best thing is to put in a feature request to Amazon (you can do that through the official Amazon app) because it seems to be their issue.
I use the IFTTT trigger method, because then I can use any phrasing that I want. So you could say “Alexa, trigger close blinds” and that should always work. But it does require using the “trigger” phrase format.