amp-lightbox not working after browser back, requires page reload

I'm testing the use of amp-lightbox to display a full-viewport navigation menu on mobile devices. Links in the amp-lightbox navigate to pages as expected, but when testing, the `Open lightbox` does not function as expected after returning to the page using the browser back button. The amp-lightbox button simply doesn't open the amp-lightbox. After the page is refreshed, the amp-lightbox will open as expected.

Start by reproducing the amp-lightbox navigation flow on a mobile browser: open the lightbox, follow a link, return with the browser back button, and try opening it again. Compare this with a refreshed page and determine what prevents the button from opening the lightbox after history navigation; done means the reported flow works without requiring a reload.

Written by the indexing model from the issue text.