Audio distortion when mixing h264s bug?

I noticed audio distortion, both in timeline and rendered out, when fading h264 movie.

I'm compiling a show reel from a collection of h264 files, selecting segments from each completed film, and cutting together. Reasonably, I used cross fades between cuts to smooth things out, you know. But, this resulted in bad distortion. Thought it would disappear in the render. It didn't. So, long story, short, here's what I came up with.
Whenever I add a cross fade to the audio of a single h264 movie, bladed (2 clips in timeline, but from the same source file)and slipped, it distorts. Also, when the audio is on separate tracks, slipped underneath, and mixed, same problem. I tested the same opporations with prores of the same movie. There were no problems. I tried several other h264 files, all exhibited the same distortion. I have not tried any other file types. If fading two clips of different sources, no problem.
System and software updated to latest.
Unfortunately it's a deal breaker for this project, had to go to another nle.

Hopefully, we'll see the promise of audio improvement in the next few days.

I would convert it all to a different format and try not to mix H.264 audio. H.264 is a bad format for post in general. If the sound was just a normal 48kHz WAV file, you'd have no problem.

H.264 is also stressful for picture, because it requires decompression and more overhead from the CPU.

i'm pretty much of a newbie to resolve, but i long ago realised that working with many popular codecs, such as h264 just wasn't worth the hassle. i've always transcoded such material to nle frendly formats and have never had any problems.

it would seem that many newcomers are looking for an all in one solution and expecting resolve to offer what many prosumer nle's offer in the way of in and out codecs. it doesn't, and i hope bm don't start wasting time and energy trying to satisfy such wishes.

handbrake has been my goto encoder for mp4 for many years. a job it does extremely well and reliably.

Oh, I forgot to mention, all of my problems happened AFTER the h264s were optimized to PR422 in the media page.

Why is it that H.264 shouldn't be the type of codec to work with in an editing?

What is the mayor difference between different codecs,
Isn't it a good thing for a software to accept well most formats instead of justa few selections?

Because H.264 is optimised for playback, not editing.