Isolation can create a low frequency issue only if the acoustic treatment is done improperly. Norman Varney could enter in here with more detail, but what I know is that if you have a wall which is leaky, that can reduce some low frequency buildup. But a leaky wall invites leakage (poor isolation). You’re not damned if you do, damned if you don’t, once you create a totally sealed (non-leaky) wall you have to do even more significant trapping to deal with the bass nodes which did not escape out the leaky wall! That’s what Bob Olhsson was referring to.
I see that just below, Bob Olhsson amplified on his post and referred much to the same thing regarding acoustical isolation.