Tasks can't be created when an issue is made confidential using the sidebar

Summary

Tasks can't be added to an issue when it has just been made confidential.

Steps to reproduce

• Create an issue
• Set as confidential from sidebar
• Try to create a task

Example Project

https://gitlab.com/gitlab-org/plan-stage/test-project/-/issues

What is the current bug behavior?

Task creation fails with an error.

What is the expected correct behavior?

A task is created.

Possible fixes

Set the confidentiality value to true for tasks created after an issue is made confidential using the sidebar.