There are quite a few things that are unclear in your post.

When you say "crew", do you mean that you burnt 800 experts on several sailors or on only one? You can very easily get a situation where you try 80 conversions on several sailors with 160 vets without a single success.

With "VIP", you presumely mean premium account?

And were your conversions before or after 00:00 server time today?

800 on 1 crew with 160 vets. after 00:00 with premium...And I burnt 400 on the other crew with 150 vets, still get no vets. It looks like noraml rate without boost. 

well check out my vet convertion lvl 79 sailors 0vets burn 100experts = 40=70vets next 100experts reach 60=90vets 300experts 80=100vets 500experts = 100=110vet   now im fine with this sailors

i have prem but still the vet convertion that is 250% i think isnt working well this is like a gamble you have to try it to see how it works

and it works not good for me

i dont think this guy knows english to well

Dont bother with vet conversions unless its 300% or more. Anything under 300% is just too unreliable.

vet conversion boost event is a BIG LIE ... to encourage SUCKERS who will burn all their crew for NOTHING ... today (event day) I used 1000 experts on 2 sailors (I would use them anyway even if it is not event day) -> 30 vet gained ... SDE love when you fill up their pockets ... and what u get for paying $ ? CRASH & LAG ...

sorry sovet but its an offer from sde which should be regarded as a mouse looking at a snake and thinking its got a chance..well  a chance but not great...