Stand-Alone Slave DTM "Extended Diagnosis" section disappears on second opening of the Diagnosis interface, if the DTM remains connected

Bug Description from Tester:

 EtherCAT Stand-Alone Slave DTM "Extended Diagnosis" section disappears on second opening of the Diagnosis interface, if the DTM remains connected to device.

Steps to reproduce:

1. Start CS and create a Solution

2. Add EtherCAT Stand-Alone Slave DTM and assign proper hardware device

3. Download default configuration to device

4. Open EtherCAT Stand-Alone Slave DTM "General Diagnosis" interface

5. Close EtherCAT Stand-Alone Slave DTM "General Diagnosis" interface

6. Open EtherCAT Stand-Alone Slave DTM "General Diagnosis" interface again and check, if "Extended Diagnosis" section is available

Expected result:

EtherCAT Stand-Alone Slave DTM "Extended Diagnosis" section is available.

Actual result:

EtherCAT Stand-Alone Slave DTM "Extended Diagnosis" section is missing.