Anyone have broken newsletter images after switching to SSL?

Hi all, I know Mailpoet is no longer supporting this version but I was wondering if any of you have this issue. After switching to SSL, newsletter images appear broken. I’m using SendGrid for the mailings. The newsletter preview works fine, as does the ‘see the newsletter here’ link at the top of the newsletter. Site has been checked for mixed content and all images are working fine.

Anyone have any ideas? Many thanks in advance.