Then you haven't played a full barrier restoring vanguard nearly enough. It happens, and it happens quite a lot, in laggy environments. I've never used bonus power myself, so I can't say if there's a correlation between those two things, but if you say you never experienced it with barrier evolution then I am inclined to say it's just a coincidence.
I have legit never had that happen with Barriers Restored. I've had charges that didn't quite work right but still gave me my barriers back, but I've never had the cooldown WITHOUT the barrier, even in the laggiest off-host games I've ever had.
The bonus power version without the barriers and the cooldown happens to me ON HOST. And I was experiencing this when home alone, so no torrenting roommates or anything.
Maybe you're right and I just got lucky with the Barriers Restored variant, but I HAVE played vanguards specifically for over 150 hours, easily (My 300 before was more like what it took to get BOTB. I stayed in Silver too long.) and if you play it that long without encountering the glitch, you change one variable, and then suddenly you're saturated with glitches? Sure, correlation does not equal causation and all that, but it IS a scientifically sound hypothesis that if something changes drastically with one change in variables, that the change was likely caused by that one variable.
I'm going to experiment again next time I play, maybe the servers were just having a very awkward week.