presonus Ampire issue

[Lau]

Hi,
when I insert Ampire on an track, knobs are not responding at all (amp or pedals). As soon as I change a pedal or amp, knobs become functional again.
I've tried several Reaper versions and this issue appears with v6.27 til v6.35 (no problem with v6.26). I've looked at v6.27 changes but got no idea of what it could be.
I don't know if it's a bug or due to a new parameter I haven't seen.
Thanks to tell me what it could be