error when cloning "The kernel appears to have died. It will restart automatically."

[StuartMoore]

i'm trying to copy an item from one orginsation to another using an AGOL notebook but i get this error for a particular feature service

"The kernel appears to have died. It will restart automatically."

any ideas?

[StuartMoore]

i've tried the same notebook in pro and get a more of an error message

\nField LEAKAGE__1 has invalid html content.\n(Error Code: 400)

has anyone had to deal with this type of error 

thanks