I don't know if it's supposed to fix that problem in particular, but I would imagine so (I have not seen a "release notes" that describes what was changed in the firmware).

The problem you are describing, I believe, is one in which if the mains were set to "Small" in Bypass Mode, they would still have some type of low-pass filter applied (thought it did not seem to follow the crossover frequency as directed in the Settings Menu). The complaint was that when in Bypass Mode, the mains should always receive a full range signal, and they were not.