Media Upload Issues

Here is my site: https://www.morningstarstudio.ca

Since upgrading WP, I no longer get a pop up uploader box when I try to insert any type of media. After a few click, I get redirected to a full screen version of the uploader, but when trying to insert the image, the screen goes blank.

I’ve tried de-activating all plugins- no help.

I’ve reset to the default wordpress theme- and that solved the issue!
But I’m trying to figure out how to keep my current theme now (Koi by Themify). Just wondering if anyone can think of anything right off the bat?
thanks