Lightbox jumps around on opening

I have Easy Fancybox set up to load an iframe with a team members bio at https://bloomonline.co.nz/pingar/about/team/

When you click on the link that opens the lightbox, the lightbox starts out at the top left of the page at a large size before centering on the page and resizing to the correct dimensions.

Would really appreciate some help to fix this.

Thanks
Meg

https://www.ads-software.com/plugins/easy-fancybox/