pro tools 11 stops recording during 96khz sessions with focusrite scarlett 18i20

I'm experiencing continous issues and incident during recording sessions with rate above 44.1khz/16bit.
I tried to record at 96khz (this is the sample I would use for my productions) , but pro tools repeatedly stuck recording after few moments.
I'm going crazy trying to do everything to make a decent and continuos recording sessions.
I've changed the asio buffer size in scarlett mix control (5, 3, 1, ms), I've tried to change the routing mode of mix control to ZERO LATENCY, I've set the windows recording and playback devices to the same rate of the mix control and of pro tools.
In protools, cleared many times the preferences folder, tried to change the buffer size, but it seems impossible to slow down it under 1024 samples .
In focusrite asio panel it happens the same stuff.
But for me, it is impossible to work at Focusrite asio panel at 1024 samples and pro tools 1024 samples.
TOO MUCH LATENCY FOR LIVE RECORDING ('ve simple tried to record three drums track at the same time.
Clear pro tools preferences, installing beta drivers from focusrite and mix control from Focusrite beta, all the stuff.
Please anybody knows the exact configuration path to record without issues or stuck for
1) scarlett mix control
2) playback and recording devicese in windows 7
3) pro tools playback engine
4) pro tools hardware setup.

already contacted the focusrite support many times.

thank you for helping

Configuration
system: windows 7 sp1
pro tools 11.3.1
scarlett mix control version 1.9.64.4 beta
driver 3.1b8
firmware version 634