hello Lucia
i tested on iOS 10.3.3 with Chrome Browser.
After your mail i tested iOS with Safari as well – here AB loop and all other functions work fine.

On MacOS Mojave 10.14.4 everything works with Chrome.
On Safari AB-Loop is there, but Full screen causes a blocking of AB and exit of FULL screen doesnt work.

This means we can work also on iOS 10.x.x with Safari, other than i thought in the first place. I was confused about Safari on Mojave and only tested Chrome.
thanks and greetings