1. Start a new block editor post in the app.
2. Add a video block.
3. Add a video from the site's media library.

Expected: The video will load in the editor with a play button.
Actual: All I see in the editor is a black rectangle.

The video was added to the post as expected (it loads when I view the actual post) but it never shows up in the editor. Videos I uploaded from the device or captured directly while in the editor appeared as expected, so the only issue seems to be with videos added from the media library.

Tested on iPhone XS, iOS 12.3.1, WPiOS 12.7.0.20190617