Missing Checkout Button (this might help)
 

In case anyone is looking for more information on this situation, here's something I've found:

I'm currently using X-Cart version 4.6.3 along with X-Payments and have "Paypal Payments Pro" (Paypal API) as my processing method. I, too, have noticed what seemed to be my checkout button disappearing randomly. There is a "Continue Shopping" button but no Checkout/Paypal express buttons. What I discovered is that the button "disappeared" whenever I configured my one SUBSCRIPTION product. When I unchecked the "this is a subscription" checkbox on the product details page for that product, the checkout button reappeared.

Apparently, even though I DO have a Payment Method selected and configured (Paypal Payments Pro correctly), it seems either the payment method or X-Payments is not configured correctly/completely to handle the subscription, and so X-cart disables the checkout button.

I'm actually still working on fixing this as I've done everything according to these instructions (it's probably the chron.php feature since I haven't figured out how to do that yet)
http://help.x-cart.com/index.php?title=X-Cart:X-Payments_Subscriptions_and_Installments#Getting_st arted_...d_Installments

In any event, just wanted to share this with any equally befuddled X-cart customers!

Re: Missing Checkout Button (this might help)
 

Hi Walt,

I must admit this is a bug in the module (X-Payment Subscriptions and Installments).
But the good news is that it has already been fixed and the patch is available free of charge. Also, the upcoming X-Cart 4.6.4 will have it fixed out of the box, too.

I'll post the patch with my next message here.

Re: Missing Checkout Button (this might help)
 

Here comes the patch.
Attachment 3802

IMPORTANT NOTE:
If it does not work for your copy of X-Cart consult with your technical support engineer - it may be caused by incompatibility with some of the customizations you might have or with our version of X-Cart or it could be applied wrongly.

Re: Missing Checkout Button (this might help)
 

THANKS! Will implement the patch over the next 48 hours and let you know the results!

Re: Missing Checkout Button (this might help)
 

IT WORKS!! Thanks so much!!

So, just to recap:
It now appears that X-cart is recognizing X-Payments/Paypal Payments Pro as a valid payment method even if the chron feature necessary for the X-Payments Subscription module has not been configured (which, in my case it has not yet been), and will now show the checkout button.

Thanks again!

p.s. It should also be noted that upon viewing the cart, I notice that "Paypal Express Checkout" remains visible as a checkout option for this subscription product. I guess the next logical question is: Will Paypal's Express Checkout backend recognize that this is a subscription and recharge the customer at the specified interval? In my situation, the reason this product exists at all is to provide an ALTERNATE subscription option for those customers who DON'T want to go through Paypal and would rather use their credit/debit card. It's unlikely, therefore, that someone who has made it this far in the checkout process will click on Paypal Express as an option, but perhaps a fine tuning of the process should disable the"Paypal Express Checkout" as a payment option when it comes to subscription products. Just a suggestion! :-)

Re: Missing Checkout Button (this might help)
 

That's a good note indeed, Walt!
We do not support recurring billing for PayPal Express I believe.

The reason PayPal Express button is displayed is a requirement from PayPal to have that button displayed at all times a merchant uses PayPal in X-Cart. This is their condition to have our PayPal integration approved officially.
Also, they have something in their merchant agreement about that.

See http://forum.x-cart.com/showpost.php?p=371816&postcount=58