Are you getting a 403 error even though you have the necessary TTS permissions? This can be because your Jira Cloud instance doesn't have the necessary permissions. SLA is a third-party app and it needs some Jira permissions to work properly. To fix this, make sure you have
atlassian-addons-admin added in Global Permissions. If that doesn’t solve the issue, go to your project settings, and on the Permissions page, add
atlassian-addons-project-access to Edit Issues.