Portfolio Modal Flashing then Disappearing

Hello there,

My site is https://www.ryankoenig.com. I just installed the most recent update, combating several bugs along the way. One that I cannot figure out pertains to the portfolio section. Before updating, I could click on one of the portfolio thumbnails and it would take me to a preview modal, which would then take me to the finished product. Now, when I click on a thumbnail, the modal flashes briefly before reverting back to the original page. How do I get this to remain instead of flashing?

The base code for the modal can be found towards the bottom of template-portfolio.php.. Is this perhaps related to https://wptavern.com/wordpress-4-4-to-deprecate-the-wp_title-function? I noticed there were several title functions in the code. Also, I checked the author’s support page and couldn’t find anything related to this issue. My backup file seems to be corrupted as well. Ugh, sorry for the novel. All help/suggestions are appreciated!

Thanks!
-Ryan