Upgraded from 1.1.20 this morning on of the sites we manage and found that none of the Internal Links popups that were working (verified just before update). It just opens the box but sits and spins.

e.g. "Color Options" on
https://www.pooltablefeltcloth.com/simonis/product/860hr.html

Regular old image popups work fine, e.g. the top 3 images on
https://www.pooltablefeltcloth.com/k-55-tour-edition-cushions-1-3-4.html

Tried in Firefox 37.0, Chrome 41, IE11, and iPad Safari IOS 8.2.

Unfortunately I don't have a copy of 1.1.20 to roll back too.
Any chance I can get a copy of that?

I don't want to upgrade any other site but cannot fix this one unfortunately.
The most recent version i have a copy of is 1.1.17.

PS Forgot to mention I also tried just not setting the type of popup too, same result. Seems to be if linking to any page, not just Internal Links.
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