This is a weird issue, but can you only edit posts from the same machine (IP address I assume) as where you posted it?
Meaning, if I upload a video at work, when I'm at home on my phone looking at PPK, logged into the same profile, I don't have the edit button letting me fix my posts. I'm a typo and bad-linking machine.
Or is there some other issue that gets rid of that button that I'm not aware of. I'm pretty sure it's the first issue, because I've checked both at once and only seen the button on the same machine.
You can only edit your post for a limited time. Something like 15 minutes I think? After that edit isn't available. Are you trying to edit a while later?