Something I've been noticing WRT Chinese flankers, the first inner pylons from the wing tips have traditionally always been used for IR missiles, whereas Russian flankers have shown to be able to carry R-77s, is this a doctrinal thing to only carry IR missiles on the outer 2 pylons per side or is it simply unable to carry a Fox 3 there? The only exception I've seen is a J-15 carrying a PL-12 on the second outermost pylon.
No idea on the Chinese Flankers.
But possible theories, cribbing from the F-16 where hanging the AMRAAM instead of AIM-9 on the wingtip pylon reduced wingtip flutter, to the point that captive (trg rounds) are hung on routine flights that don't call for it.
Not saying this is the problem for Chinese Flankers. Just that sometimes, the truth is stranger than fiction.
A bigger issue is that adding heavy weights to the wingtip messes with the moment of inertia, and since flankers are twin engined (widely spaced no less) heavy fighters roll rate can suffer if missiles are mounted too far away from the centerline. In Golden Helmet exercises the preferred load out is PL-12/15 mounted in the tunnel between the engines and PL-10/8 mounted midwing.
Conversely, the theory that heavy BVR rounds would be expended by the time a merge (and roll rate) is required - so mount them outside, expend them at BVR and keep the remaining weight as close to centerline as possible as one approaches towards WVR .
DACT does not fire off AAM nor drop AAM dummy rounds - which means it is dead weight which is carried throughout the entire mission profile, hence a preference to carry them inboard.