We're investigating an issue with Speed Review on the Android app which prevents the mode from launching/loading as expected. This will only occur on devices with Android 7 or below.
Our team is currently looking into this and we hope to have it fixed in the next release. Please make sure you keep your app updated!
In the meanwhile, please consider reviewing your items with Classic Review or Listening Skills instead. You can also still use Speed Review on the website.
Thanks for your patience.