I'm using Reason 11 and the GQ-7 graphic equalizer.
When having the HCF frequency set to something in the automation to somethiing before audio goes through the EQ,
the audio will go through fully for a split second, as if the HCF was all the way up.
Here's a video demonstrating it https://youtu.be/YzjkZWyiX14
I'm using reason 11.3.9d22 with v1.6.0 of the qualizer