While aligning a external audio clip to a video with embedded audio, it sometimes can be off by a frame or two. (or half a frame). I just edited a video and didn't bother to listen to the in-video audio track vs my separately recorded audio track and found lip sync issues after render (didn't really notice them with proxy clips and 540p video in the preview monitor). When I turned on the embedded audio track, and played both audio clips together, It produced a echo. Manually adjusting the audio clip back/forward by 1 or 2 frames typically fixed it. Although, being able to adjust by 1/4 or 1/2 a frame would prove useful too as it still had a hint of a echo on one clip. This didn't happen with every clip. Also, I use a Clap board with all my takes as well, so, shouldn't be ambiguous. Additional info: Files are .MOV files including the audio only (which appear as full video but, I just ungroup and delete the video channel) Hardware: iPhone 12 Pro MAX and iPhone 8 for Camera's, iPad Air (Gen 3) as the audio recorder with a RODE GO II Wireless mic. 1080p 30fps.