I have a store on my multisite network set up using paypal with sandbox on. If I use chrome, I am able to get through the checkout process fine. It takes me to the paypal sandbox and everything works great.
When I use safari, I get to where I fill out my shipping information, click continue checkout (which in chrome took me to paypal) and it takes me to a page on my site that says "Payment Information" and there is nothing on it but the continue checkout button. If I hit the button it gives me an error, with some information like I didn't fill out a form or something. I'll attach some screenshots.
I find it very odd that a browser would act differently in this situation, but that's what seems to be happening.