Mark, you need to close connections from Web Gateway to IRIS, so that Web Gateway reconnects and CSPSystem logins with the new role. You can do this in Web Gateway -> Status page -- close button for the second table. Or just restart the web server.

Note -- Roles field in the Audit details. Check that it has %DB_SRFT role when happens again.

If you can select from this stored procedure then you can try to use this select in INSERT into.

Does the following work?

SELECT * Custom_MENS_Other.samplesp('2021-11-02','2021-11-04','H001')

See Table-Valued functions section:
https://docs.intersystems.com/ens201815/csp/docbook/Doc.View.cls?KEY=RSQ...

And INSERT with SELECT:
https://docs.intersystems.com/ens201815/csp/docbook/DocBook.UI.Page.cls?...