[MSL] Importing steps fails for tests with 'Managed on library' steps

[Manual Step Library] It's not possible to Import the MSL step

Preconditions 

1. Xray project is created
2. Manual Step Library is enabled

Steps to reproduce

1. Create a Test A with 'Managed on Library' step (Add step -> Import Step)
2. Create another Test B
3. Open Test B view page
4. Click Import -> From Test -> Select Test A with MSL step
5. Pay attention to the MSL step details (Action/Data/Expected Result)
6. Select the MSL step and click Next
7. Map all the fields and click Validate

Actual result:  

Step 5 - No data is shown for the MSL step

Step 7 - It's not possible to import the MSL step from another test

Expected result

A user can Import the MSL step from another test