SOLVED everything is okay it was a small misunderstanding
I played a hard mission, in which I made a lot of points and i did not receive the reward for tier 8. I jumped from 7 to 9!
I started a new game to test this bug and I have the proof.
I started the new game with 39 keys from explorations
from the first mission I won 43 keys
plus the bonus of 50 keys for the first mission
the reward from tier 1 is missing in the value of 30 keys and from tier 2 I received 62 keys
in conclusion all the keys received 39+43+50+62=194 …!!the keys at tier 1 are missing!!
This could be repeated and can be a major loss of keys at a higher level even if it can happen very rarely.