ProChannel EQ HP/LP slope and uneven frequency response

[wunderbier]

Hi. I was routing a bass track into two aux channels, one with a HP filter and the other with a LP filter, so that I could add saturation to only the high end. This worked great and I had the idea to group the LP and HP frequencies together. This also worked great for adjusting the crossover point. I took it one step further and grouped the slopes as well. This did not work so well! I noticed that outside of the 6, 18 and 24 dB/oct slopes the HP and LP filters worked quite differently. I was able to un-group the frequencies and change one of them such that the crossover didn't alter the frequency content. I was also able to regroup them at that point and linearity was preserved across the spectrum. Most of the other slopes behave quite similar to each other.

So why do the HP and LP slopes behave differently at the same cutoff points? It really seems to be a simple offset problem. I was also able to group some third party EQs in a similar fashion and some of them worked well across all slopes and others required the same finessing. It's not a big deal and I can account for it with a template, but I'm curious. I've sort of noticed this already when using just a HP or LP on a track and having to adjust the frequency based on which slope I've picked, but I've never put too much thought into it. Is it a bug?