Hello @Bart_Marketing ,
This is an issue that just recently cropped up, and our engineers are still collecting data on it. I've gotten your case over to the engineers so that you'll be notified as soon as they have an update.
In the meantime, if you need to get your email sent out, I'd recommend either inserting a text link or button link, or you can take a screenshot of the thumbnail and then hyperlink that in an image block. If you'd like to the use the screenshot method, and you're unable to capture a play button overlay, there are several 3rd party websites that you can upload your screenshot to get that overlay.
Hey @Bart_Marketing , thank you for your patience as we looked into this! The good news is we have received word from our engineers that this issue has been resolved as of May 16, 2020. If it is still occurring or if you have any additional questions on this, please don’t hesitate to respond to this post as we would be happy to assist you further.