Missing Blue orb

[Kyl542]

So i've been following a guide on my 2nd playthrough to collect all blue orbs.  I finished mission 16, which is the last mission till you can get all blue orbs, entered Secret Mission #20, completed it, but no blue orb was given to me. Why is that? im currently at 3/4 blue orb fragments and this is my last one. All guides and videos i saw all have been rewarded a blue orb fragment in Secret Mission #20 on Mission 16.

 

Also i'm pretty sure i collected every orb so far, as i was following the guide step by step in every mission and even counted the orbs myself.