When we try to load our prototype in different devices and different mobile browsers such as Safari and Chrome, the size of the fixed footer is not corresponding to the one we set in our InVision prototype, and the px from the bottom are cut.
The only solution we found for that is adding a black space of 110px at the bottom of all screens, and increasing the fixed footer size. That way, Safari seems to show the footer we initially wanted to show, without any black space. However, Chrome users see a part of the black space added.
We can conclude that each browser and device is displaying a different size for the InVision fixed footer, covering part of the screen in some devices with the black space added.