Animation on page load is fine, then it's not

Sorry for the post title, I have no clue what to call this issue I am having. maybe someone can advise.

I am using an animate region on a navbar toggler / burger menu, to open a modal, and in there is all my navigation for mobile.

Take a look at https://www.pukkaevents.com, make your browser window width small enough to go mobile.

1. Click the burger menu, it opens a modal
2. Click Explore or Languages, it animates to the next frame
3. Click Go back, and you are back where you began.
4. Close the modal, and then open it again with the same burger menu icon.
   Suddenly the animation starts running on its own.

I have tried to fix it but not having much luck
There is a var set to 0, at 0 it should show frame 1, when set to 1 it should show frame 2 and so on.