Calendar problem - This content is blocked. Contact the site owner to fix the issue

I have a Wordpress site using the calendar widget in a shortcode.  

Suddenly, the page it is on is now showing "This content is blocked. Contact the site owner to fix the issue."

The code is listed below with the ids removed

<!-- MultiMonthplusRates -->
<!-- OwnerRez Multiple Month Calendar widget-->
<div class="ownerrez-widget" data-propertyId="{remove}" data-widget-type="MultiMonthplusRates - Multiple Month Calendar" data-widgetId="{removed""></div>
<script src="https://app.ownerrez.com/widget.js"></script>

We've had similar reports recently, and the fix seems to be going into the website or hosting account to "clear cache". This is not the same as clearing your computer or browser cache.

Here's a great reference article that I found that may be of use to you - https://www.elegantthemes.com/blog/wordpress/clear-wordpress-cache

Some users have also reported changing the address in the widget code from OwnerReservations.com to OwnerRez.com.

Thanks, I did clear cache in WordPress and changed the address in the widget code to https://app.ownerrez.com/widget.js, but it still isn't working.  Someone suggested possibly a firewall issue with WordFence, but I changed that to learning mode and whitelisted the IPS for ownerrez.com, but that didn't change the result either.

We've had similar reports recently, and the fix seems to be going into the website or hosting account to "clear cache". This is not the same as clearing your computer or browser cache.

Here's a great reference article that I found that may be of use to you - https://www.elegantthemes.com/blog/wordpress/clear-wordpress-cache

Some users have also reported changing the address in the widget code from OwnerReservations.com to OwnerRez.com.

Posting in case someone else4 experiences it.

My hosting provider, GreenGeeks (love them) tracked it down. It was a reference in Content Security Policy to ownerreservations.com. They replaced all references to secure.ownerreservations.com in your Content-Security-Policy with app.ownerrez.com.

Thanks Miao, that's great information! Not being WordPress guru's myself, I wasn't aware that it was at all common for CSPs to be applied in WordPress, but I did a quick search and found this article, which may be helpful for anyone else who has the same problem:

Implementing Content Security Policy (CSP) on WordPress