WebGL black screen / doesn't play on mobile devices?

I’m not sure when this started, because at first it did load (albeit slow on iOS).

The load bar DOES load, but then the game doesn’t start.

Now I just get a black screen? On both Android and iOS, but not all devices. It works on my LG V20 and Sony Xperia, but not on my others such as Lenovo with Android 5.0.

See picture

I did see the Unity logo appear in the center of the screen, but full screen button doesn’t work either. It’s like the game itself just didn’t play.

I just tried it with 128 and 256 Memory Size and with and without Web Assembly. No results.

Mobile browsers are not supported by Unity. Unfortunately I have to resort to using Cocos Creator even though I’d rather use Unity.

Is that the official reason? Because it runs fine for most of my mobile phones, just a few like Lenovo don’t run after loading.

Maybe a memory issue or…?