On some Android phones, both the Facebook and Instagram in-app browsers (as of today) are malfunctioning when an upload field within a promoted or linked landing page has the "accept" attribute. This renders the button non-functional. Opening the page in a regular, external browser outside of the Facebook app resolves the issue. This is frustrating (especially since it has been reported for some time), but a workaround is available.
The following JavaScript fix solves the problem and makes the buttons work again:
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