Not showing subgrid record

Hi, I'm using D365

I'm using subgrid at D365

But, If I delete or edit record on subgrid, subgrid doesn't showing any record at D365

In this case, record has exist. Because I can read another pages or record's number(like a 1-2 3/5)

And If I refresh at subgrid, I can read record on subgrid.

But I wonder why record of subgrid doesn't showing at form.