Item data cant save

Dear communities:
A problem about saving item data

after I click save then the message comes
whats the problem ? please provide me some suggestion

i think I found the solution that I have to fill in item group (it’s mandatory)
but why it wont give me a message like " item group is mandatory"
is this bug or I do something wrong?

Do you have custom scripts in Item?

No,I didn’t do any script adjustment