Popup Pro prevents sumbit button loading

Hi,

I am using Popup Pro to popup a page with a contact form (contact form 7) with a custom submit button.

I use, in custom css

.page-id-1060 .wpcf7-form input[type="submit"] {
background: url('https://ultimatebathroom.ca/ultimatebathroom/wp-content/uploads/2016/10/UBR-sendbut.png') center no-repeat;
background-size: 100% 100% !important;
border: 2px groove #55DEF2;
width: 200px;
color: transparent;
padding-top:30px;
}

to load the button on the page, but in the popup the button is removed. This used to work in the popup up until recently.

I am using the X-Theme and cornerstone.

Let me know if you need any further info,

Mike