After becoming a “Pro Hacker”, I had a break for ten months due to workload. Then I came back and started to hack the boxes and in last two weeks I have owned more than 10 machines. But I am still “0%”.
I know we lose point came from retired machines but it is still weird.
Is it normal?

It’s normal.

Yes. You level up by doing machines at a certain rate. If you snooze you lose (points but not your rank).