[Quest] Bizarre menu/canvas issue in Quest build, but 100% okay in editor, with video.

Not sure how much detail to include, please see video for the problem and whether someone might have general pointers that could prevent something like this from happening. It's very difficult to troubleshoot as there's no console for the build, and there are no errors or issues within the Unity version. 

video link here (sorry about the broken link as this forum does not let me post it full until I've "been around for longer": youtu.be + 0NmS5tENwQo

fwiw: PersistentObject spawns in scene, a "menu" object is child'ed to the spawned object, PauseManager finds it and makes sure it's deactivated from the start. It gets SetActive(true) upon holding down Button.Start for 1 second, a canvas / black alpha image with Screen Space - Canvas creates the fade, all buttons have shaders to allow them to be "always on top", Time.timeScale is 0 during pause, and hitting RESUME resets the time, replaces the hands, and SetActive(false) the menu object. To eliminate any issue I've removed all other scenes for both the Unity build and Quest build so there's only one scene in build. 

Thanks in advance.