After an instance upgrade, the "Tours" (Guided Tours) menu is missing on the main Service Portal page.
This can occur when the Scripted REST Service 'Resources' (System Web Services > Scripted Web Services > Scripted REST APIs) have a blank API version. Previously in London, this field was empty, however in Madrid the value should read 'v1'.
In cases where the value is blank, simply populating it with 'v1' should resolve the issue. Note that 'Resources' is a related list on the Scripted REST Service form. You may also import an out-of-box version of this record to correct the issue.