Cruise level inconsistency question.

[The Equalizer]

RJTT to EGLL A35K v1.2.1

 

Initial cruise altitude and future step climbs seem to not correspond with Opt FL or even the Max FL. Simbrief gives me an initial cruise alt of 33,000ft, ATC  gives me 35,000ft but my optimal fl is suggested as 36,000. The listed step climbs also seem out of sync if that makes any sense. If I move up to 36,000 manually, my first step climb to 37,000 is 7h 30mins away. This just doesn't feel right and I've not noticed this before the latest version.

Is this normal? If not, is it an aircraft, sim or Simbrief issue? 

Thanks in advance.