A little fly told me you were doing extract beers.
You'll find extract beers will sometimes carb differently as opposed to all grain beers. If you have an extract that's light on proteins, like hops, as it ages, it's less likely to produce a rocky, small-bubbled foam a lot of people would die for. Adding some steeping grains (Munich light, Vienna, or even wheat or rye) that could double as base malt will sometimes help.
One of my best foaming beers was a higher gravity partial mash Amber American ale done with WLP001. It was heavy on extract, but the steeping grains made a big difference. I used malted wheat as a steeping grain. The beer was primed in the bucket. Some bottles carbed better than others, so that led me to priming directly to the bottles.
My opinion is brewing with pre-hopped extract is inferior to a good partial mash with extract, good steeping grain, and packaged hops.