ALT930 TTL Encoder Test Failure

[Denys]

Hello, Hello,
I'm using ATV930C25N4C with encoder card VW3A3420 for hoist application. My incremental encoder type is POG 10DN1024R (TTL, 1024 pls. 9-26V).
As per ATV930 program manual, I used Encoder check procedure from Encoder Configuration Menu:

1. Configure the parameters of the encoder used
2. Configure the motor parameters.
3. Set Encoder usage [EnU] to [No] nO.
4. Perform auto-tuning.
5. Set Encoder check [EnC] to [Yes] YES
6. Run motor for a few seconds (Encoder check should change to done)

My encoder settings in ATV930 are:
EUCP: AB
ENS: For signals A/A-/B/B-
EUCV: 12V
PGI: 1024
Motor Control Type CTT: Sensorless flux vector V

When I operate the motor without encoder check ENC, and without encoder usage ENU, my hoist is working and I can see encoder pulse count is working from SoMove software. But when I select ENC Encoder Check Request - The motor stopped mostly immediately with ENCODER FAULT message.

I found that during motor tune, the encoder pulse count changed randomly from 1-2 pulses to several thousands. So I suspect the cable shield earthing problem, and I improved it as per installation manual by earthing the shield to the drive body. After this, during the motor tune the pulse count from encoder reduced to 1-2 pulses only. But anyway, if I select the encoder check request, the drive still going to ENCODER FAULT. It happened even before real motor movement started (brake was closed) and I already have some pulse counts from the encoder again. Probably I still have earthing problem. 
My motor is used for a crane hoist application (160kW motor) and to be able to run the motor for encoder check, I have to complete configuration for hoist application and brake operation as well. 

My question is, for the encoder check procedure, should I disconnect the motor from the crane gearbox (huge mechanical work) or I can test encoder with physical motor connection to the hoist?

And one more question, despite the earthing issue, what else could be the issue, when encoder fault appears immediately after the motor start? 

Thank you in advance.