Sometime we do not have permission to access private workspace in Azure DevOps to make it accessible follow below steps :
Global Administrator permissions –Member of the “Project Collection Administrators” permissions group in Azure DevOps Project which is linked with workspace.
Open up Developer Command Prompt for VS 2019.
Identify the workspace name and owner:
tf workspaces /owner:* /computer:* /collection:https://<site.url>/defaultcollection
Change Permission to Public:
tf workspace /collection:https://<site.url>.visualstudio.com/defaultcollection AzureBIDEV01_01;https://<site.url>.visualstudio.com\<username> /permission:Public