I am having a similar problem as described below.
I have a site made in VueJS, backend is symfony PHP. php.ini allows 16M uploads a VueJS component for the upload: "vue-picture-input": "^2.1.6",
And the relevant config: accept="image/jpeg,image/png" size="16"
However, when I upload from desktop it works, image is saved. When I upload from a mobile browser it does not.