Here’s something…
I was building an options page with a repeater field and had the same problem as the widget, no matter what I did it wouldn’t save the repeater field.
Found this support page where Elliot Condon mentions that the Field Names might be too long and not saving properly in the database.
So I shortened my name field and dropped a bunch of underscores and it worked! I then went back to my widget and did the same thing made the name field shorter and dropped my OCD underscores and it worked!
Hope this helps, reply if you get it to work.
Cheers
