Safari buffering/freezing — Related to MediaPackage adding "autoplay=1" sporadically?

I'm having some issues with a MediaLive/MediaPackage stream buffering/halting and jumping bitrates all the time on Safari (desktop & mobile), but not on Chrome. Both using video.js as a player, as well as a native video tag.

I'm using Elemental Link devices to push to MediaLive. Using a configuration generated by the MediaLive Workflow Wizard, but modified slightly to add tagging and an additional bitrate. I also had to modify the CloudFront distribution a bit to get around CORS issues, allowing "Origin" as a caching key.

I've run the MediaPackage stream through Apple's MediaStreamValidator tool. It's flagging as an error that MediaPackage is sometimes returning an "autoplay=1" to the individual manifests, and sometimes not.

For example, some pulls of the manifest return chunk URIs like this: index_1_16087.ts?m=1642705601 and other pulls return this: index_1_16087.ts?autoplay=1&m=1642705601

Here's a sample MediaStreamValidator error:

Error: Media Entry URL not match previous playlist for MEDIA-SEQUENCE 16087: index_1_16087.ts?autoplay=1&m=1642705601 vs index_1_16087.ts?m=1642705601

Could anyone please advise on how/why this autoplay query parameter is being added, what effect it's expected to have, and if this might be causing the problem with Apple devices?

Would also love any other advice on getting a MediaLive/MediaPackage stream to play smoothly on Safari.

Thanks!