Hey Tom,
Welcome to the forums and thanks for choosing PRO! I’m sorry to hear about the troubles and I’d be happy to help get you started in the right direction.
These types of support requests typically extend beyond the scope we’re able to support as it appears to be a conflict with another plugin. With that said, I’m not too familiar with All in One SEO Pack, but I do know with Yoast’s WordPress SEO, you have the ability to set the featured image for individual events. You can also set a default image for you entire site. You may want to dig a bit deeper into the All in One SEO Pack settings and/or reach out the authors to see if they have any insight as to fetch the correct image.
I wish I could be of more help but per support rules, theme and plugin conflicts are out of our hands. Thanks for understanding and best of luck resolving the issue. Have a great week!