My imported videos now just play the AI generated English audio from YouTube instead of the original audio track and the option to change it is no longer there. iOS app and safari webapp on mobile. Don’t know if problem exists on others. Makes all my imported videos useless.
EDIT: feature still there on Safari on Mac
Cheers for the help LingQ 
Sorry about the late reply here, not sure how I missed this thread. I apologize!
In some cases, we are unable to import original lesson audio. What you can do in those cases is to use an available online tool to extract the audio and upload it to a lesson. You can do the same for importing videos that don’t have subtitles available.
Check this thread for more details: How to import Youtube videos without captions