Firefox not respecting https/http rewrites

all browsers seem to be working ok with the exception of firefox.

i completely cleared the browser cache and cookies.

and when i click on my checkout page

https://a1decals.com/products-page/checkout/
its supposed to go to the secure page
https://a1decals.com/products-page/checkout/

and it does in all browsers but firefox.

im trying to patch this with an htaccess rule but its not working either.

Options +FollowSymLinks
RewriteEngine On
RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteCond %{REQUEST_URI} products-page/checkout
RewriteRule ^(.*)$ https://a1decals.com/products-page/checkout/$1 [R,L]

https://www.ads-software.com/plugins/wordpress-https/

can anyone give me any idea on what to do for a fix?, i tried rewriting the checkout page link, but it due to another ssl plugin that link gets rewritten to the same http as the security for the page accessed.