Firefox / uBlock Origin only showing camera / image apps when clicking on a file upload button
As confirmed by OP this app resolved the problem App Picker Classic. From app description


  If you have app choices that are currently hidden - maybe you chose "Always" by accident once, but you'd like to be able to reinstate the app and choose each time - then reset these by clearing the defaults in the application manager of your phone/tablet.


In addition, this app permits working with some app intents and resolves common URLs. One needs to install the app, reset defaults and enable required app.

Note

Despite the app being not updated for last two years, it even works with Marshmallow, as can be seen from @Arlinds answer here - which was a surprise to me, and the reason for remembering it !