User is not able to start validation task

[KaterynaKovrizhnykh]

Preconditions:

1. Extraction is done with type "Extraction and annotation" with "Hierarchical validation" validation type, and an admin as an annotator and validator

Steps to reproduce:
Go to BadgerDoc platform
Select the extraction from the preconditions
Do some annotations and press "Finish labeling"
Create a validation task

Expected result:
User is able to validate the annotations.

Actual result:
The validation is in "Pending" status.
All buttons are muted, user is not able to perform validation