The Mac app transcodes all media as audio proxies (i.e. without video) by default.
To turn on videos proxies, follow these directions.
Before adding your media, click on the purple + icon in the Drag and Drop box three times
Once clicked, a video emoji will appear before the words Drag and Drop.
To turn off video proxies, click + three times and the the video emoji will disappear.
Related Help Articles:
Best Practices for importing Multicam and Sync clips with the SS FCP X Extension
Can I translate my subtitles within the FCP Extension?
Export burnt-in subtitles/caption in FCPX
Exporting video proxies from your NLE to preserve timecode/framerate through to transcript export
Features of the Simon Says Mac app (a visual guide)
How can I use the transcript editor?
WYSIWYG Subtitle Editor