Sometimes there can be an issue with the payment by card in the PayPal Plus Mexico integration.
An infinite progress bar can be shown instead of the form for the payment by card :
In this case you have to check the URL of your checkout page and verify if there are any specific symbols.
The issue with the display of the payment form is connected to the wrong symbols in the URL :
This URL is sent to PayPal as “cancel_url” and if it is invalid, the iframe is not shown by PayPal.
If you go to your PrestaShop Back Office – Preferences – SEO & URLs you can see that the “order” URL contains a space in the MX version.
In some version of the PrestaShop there can be some incorrect translations of the URLs. Normally there should be no spaces to the URLs.
If you modify this field and delete the space, the issue will be resolved.
Once the modification is done, please check again the URL in the Front Office and try to pay via PayPal module.