That's kind of hard to see in those pictures, a bad angle, but it looks like for sure the pins aren't dropping far enough down. I don't think that your SSQA lever is fully locking down. As others have said, you have to catch the attachment on the top channels and then roll the bucket back and maybe (carefully) kind of bounce things around a bit. There are issues with different attachments fitting various loader SSQAs, so maybe this is one of those? I know that there was a service bulletin for Kioti NXs late last year. I'd check with your local Kioti dealer if any of that could apply in your case.
PSA: Whatever you do, DO NOT have your loader in float mode AND your foot under the loader ends while disconnecting the attachment! I dropped a loader arm end right on top of my foot. Fortunately I'm pretty quick (physically, mentally it's a different story!) and I yanked my foot back, slipping it mostly out of my (rubber) boots. WTH was I thinking? (I was thinking that things were on the ground because the attachment was on the ground!) Generally I think through safety things.