Catalyst CX 100 does not maintain stable sustain but generates a kind of wah wah effect.

[Morningstar0459]

This happens when playing chords, not single notes. With any voicing, noise gate on/off, it's not the presence or boost knob, and I'm going crazy because it's impossible for an amplifier like this to be unable to handle sustain properly.

[rd2rk]

Back up your presets and perform a factory reset.

If that doesn't get it open a support ticket.