amp-sidebar not opening in the viewer in FF

[Enriqe]

Trying to open the amp-sidebar in an AMP doc opened in the viewer from the Google Search results page results in a failure. The opacity of the story is decreased (expected) but no sidebar is opened (unexpected).

A suspicious warning also appears when clicking the sidebar:

[FixedLayer] In order to improve scrolling performance in Safari, we now move the element to a fixed positioning layer: 
<amp-sidebar id="story-sb" class="style-1 i-amphtml-layout…idebar i-amphtml-layout" i-amphtml-layout="nodisplay" layout="nodisplay" side="right" role="menu" tabindex="-1" i-amphtml-fixedid="F0" style="pointer-events: initial; top: calc(0px);" open="">

Steps to repro:

1. In firefox mobile emulation, search "fun things to do in nyc"
2. scroll down until you find the corresponding story. (https://www.google.com/amp/story/s/travel.visualstories.com/fun-things-to-do-in-nyc)
3. try opening the sidebar

[gmajoulet]

Is it a Story specific or AMP bug? Did you try the feature in a regular AMP document?

[Ichigo3d]

the Side bar feature works properly in the amp page

[Ichigo3d]

[Enriqe]

I think that screenshot is from Chrome, and doesn't look like it's opened from the viewer, though? Could we confirm this in an AMP document opened in FF in a viewer please @Ichigo3d ?

[Enriqe]

I think we'd need to try it on an AMP page opened in the google viewer, I don't thing the amp.dev sample is opened in one.

[Enriqe]

Searching for [balance-positivo-para-el-segundo-fin-de-semana-con-salidas-recreativas-en-carlos-paz] and opening the AMP doc in FF yields the same results. This is an amp-sidebar bug. @ampproject/wg-components

[kevinkimball]

We identified that this was due to an error with the testing environment (Firefox tests were using a iOS 12 user-agent, should be using modern UA that does not use FixedLayer).