Sounds like dimming the can lights changes the load on the vent panel by a very small amount, and most anything LED seems to have a problem with fluctuations.
I bet if your can lights were incandescent or fluorescent there would be no problems at all, and that change might be a good solution.
A lot of LED bulbs do have some tendency to act a bit crazy when other things are on the same circuit.
I installed LED bulbs in a ceiling fan and they wouldn't light unless I had one incandescent in the fixture. Just a weird LED issue.
I also have 8 LED can lights in the kitchen, and when first turned on, one light comes on, followed by the rest after a moment. Another weird LED issue.
I bet if your can lights were incandescent or fluorescent there would be no problems at all, and that change might be a good solution.
A lot of LED bulbs do have some tendency to act a bit crazy when other things are on the same circuit.
I installed LED bulbs in a ceiling fan and they wouldn't light unless I had one incandescent in the fixture. Just a weird LED issue.
I also have 8 LED can lights in the kitchen, and when first turned on, one light comes on, followed by the rest after a moment. Another weird LED issue.