We don't have the problem on our end. Could you give a link to your page and the screenshots ?
Note that it might be a problem related to caching: you had an unlimited quantity with the add to cart button displayed, then changed that, but since the product page was cached by joomla/your template, the add to cart button was still displayed.
So please check these points:
Disable the cache in Joomla configuration.
Site -> global configuration -> system -> "Cache settings".
Disable, if it's enabled, a joomla cache plugin.
Check your template' options for a potential cache option and deactivate it.