I definetly used to have what I would consider to be meltdowns but not anymore.
I was thinking I have never had shutdowns, then when I was thinking about things I realised a few things that I was confused about may be explained by a mini version of a shutdown..2 examples:
1-Someone comforted me I froze, the room went blurry and I lost memory until the person was gone, I still felt a bit blurry for a while afterwards.
2-I went to an event which was fine until near the end then it all started to get too hectic and I felt very conspicuous eventually I felt like I wasn't there, like the world went all blurry and surreal. I still spoke but only when spoken to and I didnt think at the time what I was saying and had no connection to it, when I got home and sat down with a cup of tea I looked back and remember some things I said and really cringed, I would never have said it if I was focussed, it wasn't bad just thoughtless and I felt really stupid for weeks aferwards. When someone asked me a question about the event because they had seen me there and I had no idea they had been there I just tried to explain that it had got hectic and all gone a bit blurry (hadn't heard of shutdowns or as then), they looked at me like I was odd funnily enough.