To be blunt the video didn't answer a single one of the questions Foob asked, you can't really expect him to know which world it was in, whether you checked any of your other chests, or whether they're locked using the lwc permissions from the video there.
You might want to describe a bit more of what's going on here besides just the video so Foob knows what might be wrong. Like, can you access the chest itself in your wild plot? Can you access any of your chests there? Can you destroy any of the other chests, so we know if it's just that one?
And also try GG's suggestion as well, since she's had this happen to her before and it may help solve your issue.