On my self-hosted v4.712, I decided to move all post image data to an S3 bucket a couple of days ago.
It was progressing as expected, but the dashboard shows progress stuck at 65.21%.
One thing I have been doing is uploading some of the attachment folders manually to the S3 bucket because we have so many attachments, but I don't know whether that has interfered.
I have tried clearing system caches. Cloudflare has been disabled through this entire process.
I click to manually run the tasks now, it spins for a few seconds and the errors out with an HTTP 500 error. A refresh then shows the same dashboard status: