Can't seem to add footage on the app using the LG velvet phone. Had no issues with my Google pixel 4. The footage when attempting to upload is stuck at the preparing media screen when I exit out and go back in the untitled project just shows blank (black screen) videos no sound no image.
Sorry about the trouble. As of now, Premiere Rush is not available on LG Velvet. This might be the reason you're seeing performance issues. You can check here for Rush supported devices: https://helpx.adobe.com/premiere-rush/user-guide.html/premiere-rush/system-requirements.ug.html
Let us know if you have any questions.