Yes, you are right. I cannot complete Tier 2 because custodian Rebus is available only in weekends. But is good to know that once i deliver the remaining cortex fragments i will get the Tier 3 rewards as well. Good answer.

Thank you for the clarification.

Small remark. I noticed that while custodian Rebus is available, there are no more drops of the cortex fragments. Once he disapeared, they start dropping again. I do not know if this is intended, but is really annoing if you still need to farm some of them and you cannot.

Thank you.

We put out a fix to our backend yesterday evening however it will not affect those accounts where the problem occurred already. We will manually activate your tabs!

EDIT: I just noticed your question about the rewards: you won't receive higher tier rewards until you do not fully complete the tiers below.

Actually i did not get any reward from Tier 3, including the 5th tab. How do i get them?

But hey, I may be mistaken and remember wrong.