Some seed shells are hydrophobic.
You should put a sheet of paper towel over the floaters to submerge them.
After 24 hours throw away the floaters.
I had a batch of cherimoya seeds that had 5 floaters.
Those floaters were similar in weight to the sinkers.
Only 1 in the batch failed to germinate.
I didn’t know if a sinker or a floater failed.