A while back we disabled the mobile uploads interface in mobile. It's been sitting in our codebase dormant so people can enable it via user js if necessary but it's broken a few times and doesn't seem to be getting the attention it needs.
Given there is now an editing team and from what I understand UploadWizard is being refactored into oojs ui (which will lead to it being less bulky and more mobile friendly) I'd like to suggest we abandon the code in MobileFrontend and help support that effort. Note this effort is likely to take a long long time, since that extension suffers from much technical debt and makes use of jquery ui, which is not available on mobile, so to set expectations we're not going to be in a state where we can enable this on mobile (if we wanted to which again is highly questionable) any time soon (think in units of a year rather than weeks/months).
The downside of this is any 3rd parties who are using this uploads code (it's turned on by default) will lose this feature and there is no available alternative.
I've written a patch to remove it [1] but I just wanted to post this here to give people the chance to voice any concerns/disagree with this approach.
Note: We can always restore the code later on if necessary. I argue this will be easier than fixing/maintaining the existing code. Someone could also put it into a separate extension if they wanted to use it.