Enamel paints (help!) compatibility with itself

Hi. I´m having some issues when mixing and airbrushing Humbrol enamel products.
First of all lets recall the typical statement: "you should be able to mix same type (enamel) from same brand (Humbrol) without any problems".

Problem 1: mixing Metallic + Metallic
I was about to give a coat of #51 Sunset Red + #53 Gunmetal over Gloss Red (all Humbrol enamel). after mixing and thinning I started to apply first coat. First only thinner was being sprayed, and then 51 and 53 started to be seen over the body, but not mixed. The body ended up looking red with a metallic red coat with some dark dots (gunmetal) all over it, looking like "hammered finish" paint. Weird... Please note that all this products sprayed correctly not being mixed, and that #51 and #52 where previously mixed without any problem.

Problem 2: spraying clear color
I tried to spray Tamiya enamel Clear Red thru AB, and as soon as I started spraying some kind of "caramel-like hairy-like dust" started to appear from the AB and all over the parts. I ´ve just tried to do the same with Humbrol enamel clear orange with the exact same effect. Does anybody know if enamel clears cannot be sprayed thru AB?

Problem 3: mixing Humbrol clear + Gloss
I tried to solve Problem 2 by mixing humbrol clear gloss coat with humbrol enamel gloss red. Nothing happened here. I mean, nothing got sprayed. I thinned as usual and then I guess only clear came out of the AB (no red...)

The fact is that I´m trying to solve both "clear colour" and "metallic/candy colour" needs. Clear colour is intended for tail lights. And metallic/candy is to give that kind of effect on bodies. I tried applying a silver base coat, then a gloss color coat (red for example) and the red covers completely the silver, as it where sprayed just over white primer.

I´m also considering buying Alclad Candy enamel laquer. They provide a Silver Candy base coat and a Candy enamel laquer (kinda clear paint) which looks really cool on their promo pics, but I´m affraid I will have the same problems as with clear enamels from Humbrol.

Any thoughts about all these?
Thx

I'm not familiar with spraying Humbrol enamels but I have a pretty good idea of what's going on.

Problem #1 Sometimes metallics and non metallics do not mix well.

Problem #2 The string effect you are getting is because the paints are not thinned enough. Keep thinning more until you get a good atomized spray. Sometimes thinning guidelines don't work and you have to tweak the procedure for your unique spraying equipment and conditions.