[LAU] Soundcard volume problem

[ycollette.nospam at free.fr]

Hello

I've got a focusrite 18i8 usb soundcard which works fine under Fedora 25.
But, from time to time, the sound levels are not correct.
For example, I can have a normal level on the right channel (the one saved dugin the preceding session) and 50% on the normal level on the left channel.
When I start pavucontrol, or alsamixer, all the levels seems to be correct.
To fix this, the only solution I found is to start qasmixer, to switch the problematic channel to off and then to switch it back to the last value.

I wanted to fill a bug report, but I don't know where to start.
Is it a kernel driver problem ?
Is it due to an alsa script ?

Best regards,

YC