Planning Console not working for table extended from pm_project.
The Planning Console being extended would be considered a customization not supported by ServiceNow Support.
Our Product Experts have stated that you would need to make sure that the Planning Console Columns are updated for your new table:
However, it was also mentioned that there are many Planning Console script includes which are hardcoded to query the (pm_console) table:
Our Product team has mentioned that upon creating the Custom Planning Console Columns the Planning Console will not work as expected as the Script Includes above will also need to be modified.
Those are just a few of them and there may be more that would need customization.
We would recommend using Teamspaces, which is an out of box way to provide data separation for different parts of your organization.
It is recommended to take a look at the documentation: