Half-point problems

Last friday (02/25/2022) I applied a test to my students on MS Forms, by the end of the test I gave half-point to 2 different students. Later on I tried to checkout their answers again, but it completely disappeared.

I'm sure I didn't erased their answers! By the way, it also happened to I friend of mine who did exactly the same thing I did, and the same problem occured.