I'm trying to use the In-context option without success.
The popup opens, lightbox style, seems to be trying to load for a few seconds but then redirects to the usual full page for Express.
I have read that this symptom can occur when the shop is not in the accepted country list, this is Spain so should be valid.
The source code on the payment confirmation page seems correct:
<form onsubmit="submitonce();" id="checkout_confirmation" method="post" action="https://www.mysite.es/subdir/ipn_main_handler.php?type=ec&amp;markflow=1&amp;clearSess=1&amp;stage=final" name="checkout_confirmation"><input type="hidden" value="7249fe1578a4fdfaf92fd07bcb427f38" name="securityToken"> <script>
window.paypalCheckoutReady = function () {
paypal.checkout.setup('my merchant id', {
//locale: 'en_US',
container: 'checkout_confirmation',
button: 'btn_submit'
});
};
</script>
<script async="" src="//www.paypalobjects.com/api/checkout.js"></script><div class="buttonRow forward"><button id="btn_submit" name="btn_submit_x" value="Confirm Order" type="submit" onmouseout="this.className='cssButton submit_button button button_confirm_order'" onmouseover="this.className='cssButtonHover button_confirm_order button_confirm_orderHover'" class="cssButton submit_button button button_confirm_order">Confirm Order</button></div>
</form>
Setting the PPDEBUG cookie from the console yields this info
{"status":"IC_SETUP","button-type":"JS","button-number":1,"merchantSite":"www.my_website.es","version":"3.0","token":null,"guid" :"f46da875-5c2d-7b58-260d-0715581980e3","oneTouchShowed":"false","jsBtnConfig":[]}
iframe
{"status":"IC_HERMES_PREFETCH_COMPLETE","elapsed":1203,"merchantSite":" www.my_website.es ","version":"3.0","token":null,"guid":"f46da875-5c2d-7b58-260d-0715581980e3","oneTouchShowed":"false","jsBtnConfig":[]}
I note that after cancelling the paypal page to return to the shop and trying again, the in-context code is NOT generated...?
<form onsubmit="submitonce();" id="checkout_confirmation" method="post" action="https://www.motorvista.es/tienda_155/ipn_main_handler.php?type=ec&amp;markflow=1&amp;clearSess=1&amp;stage=final" name="checkout_confirmation"><input type="hidden" value="7249fe1578a4fdfaf92fd07bcb427f38" name="securityToken"><div class="buttonRow forward"><button id="btn_submit" name="btn_submit_x" value="Confirm Order" type="submit" onmouseout="this.className='cssButton submit_button button button_confirm_order'" onmouseover="this.className='cssButtonHover button_confirm_order button_confirm_orderHover'" class="cssButton submit_button button button_confirm_order">Confirm Order</button></div>
</form>
Often I come across stuff that fails when in Spanish, but this is generated with shop language as English.
I've tried this with my in-development 155 shop and a vanilla 155 on my hosting with the same result.
Since there are few/no queries about this, I assume it usually works.

All I have done to enable this is add my merchant id. From what I can see in the code, that is all that is necessary.