"Mask" is not working on mobile

I have 2 images that I “masked” with and overflow-hidden Div.
On desktop/preview mode/mobile view on desktop, it works great,
but for some reason, it doesn’t show up on an actual mobile device.
But if I “drop the mask” (set overflow to visible) it shows perfectly fine (but doesn’t mask the image as intended).

Thank you for any help.
Here is my read-only link.