Your problem sounds very similar to a problem I had about a year ago with TCP T-8 4lamp fixtures in a new home garage.
Had various AFCI's tripping, after connecting Siemens Intelliarc tool it showed whenever those lights on it had high level of the condition that could cause trip and not only on that circuit but circuits throughout the house!
Turns out it is the electronic ballasts causing it. (I read that switching power supplies are also notorious for it in the case of an LED drivers). I started disconnecting lights one at a time, and when I got 1/3 way through readings started to drop, 1/2 way through even lower. My conclusion was that the interference was additive and just so happened that the number of lights installed was at that threshold.
Interestingly I installed a leviton receptacle type surge suppressor in one of the longest circuits in the house and it all but knocked out all the interference causing the tripping. Then found it also helped to switch which phase the interference was being injected on. Still would have a random trip after months. The latest thing I did before Christmas was replace all of the AFCI's with most current breaker as (used siemens in this case) as of June 16, 2014 they installed additional filtering in AFCI breaker. So far no reports of problems.