What's the issue?

amp-carousel jumps to last slide when the visibility of its parent container is toggled

How do we reproduce the issue?

See jsbin here:
http://jsbin.com/zosomuqezo/edit?html,output

1.Tap blue or green preview thumbnail (i.e. not first or last)
2. Tap carousel 1
3. Tap carousel 0
4. Carousel 0 now jumps to final slide

Expected: carousel 0 stays on same slide.

Note that the problem does not occur if the visibility of the carousel is toggled directly, as opposed to its parent, e.g. in this jsbin the issue does not occur
http://jsbin.com/girekiyepa/edit?html,output

(Note, the problem also occurs if amp-bind is used to interact with the carousel & trigger [slide] and [class] changes (took me a couple of days to realise the issue wasn;t related to amp-bind :'( )

What browsers are affected?

Firefox 53.0.3, 54.0 MacOS Desktop FAIL, Firefox mobile Android FAIL
Chrome desktop OK, Chrome mobile Android OK, Firefox mobile iOS10 OK

That's all I checked

Which AMP version is affected?

1496877433269