Freezing faders on mix window

[Herge]

Hello,

I got a really strange issue with Pro tools 12.8.2 :

Sometimes, all faders in the mix windows become randomly frozen (so in the S6 too..) : You can still edit, add insert and edit insert, create manually some automation, they will be written. But you can’t access to the faders on the mix window and the pan also : they are frozen.
The only way to get them back is to quit pro tools (no need to force quit) and launch again.

It happened on several pro tools session with different medias.

The issue happens randomly. The last time I tried, I had the problem on a session three time (so after 3 relaunch) at the same moment : juste after launching this session, everything works fine but when starting recording and writing autom, the freeze appears instantly...

Any idea please ?

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system configuration :

Pro tools HD 12.8.2

Z440 Single 6-Core Intel Xeon E5-1650v4 3.6GHz with 32Go Ram and SSD 250 Go

1x HDX card and MTRX

1x Kona LHi (driver v15)

1x S6 M10 16 faders (Eucon v18.3)