Export settings not working on Android

[yoasif]

Steps to reproduce:

1. Follow instructions on https://blog.mozilla.org/addons/2020/09/29/expanded-extension-support-in-firefox-for-android-nightly/ to install ClearURLs
2. Go to add-ons, clearurls, tap the gear icon
3. Tap the export button

What happens:

Nothing happens.

Expected result:

The settings file is exported and a download prompt appears, like in uBlock Origin.