Shifter only supports "Pretty" WordPress Permalinks
For example:
Day and name: http://example.com/2017/01/30/hello-world/
Month and name: http://example.com/2017/01/hello-world/
Numeric: http://example.com/archives/123/
Post name: http://example.com/hello-world/
For more info on how to setup and customize your permalinks, visit the WordPress Codex for more info: https://codex.wordpress.org/Using_Permalinks
Trailing Slashes are Required
For example:
You can set as many permalink structures as you like (whether WordPress presets or not), but never forget to add a slash (/) to the tail.