Equalizer (EQ) not working with 4.25

We recently moved from 4.24 to 4.25.3.
We were using a sound mix modifier with EQ set to modify game sounds to drop out mid range frequencies, and it worked fine.
With 4.25.3, once the sound mix modifier is pushed, nothing changes. I know it is active because (a) I can see it using ‘stat soundmixes’ and (b) if I set the LPF to 500, that works.
The sound mix modifier asset hasn’t changed since we upgraded (checked through perforce). The settings are attached.