Tokens are not being accepted in the default value field for Select options. You need to click the Manual entry link to unhide the Default value field.
Problem appears to be the #default_value_pattern value, which is using an old token pattern. This affects the grid component as well.
$ diff select.inc select.inc.old
139c139
< '#default_value_pattern' => '|^\[.*\]$',
---
> '#default_value_pattern' => '^%.+\[.+\]$',
This is the Drupal issue where this was reported.
https://www.drupal.org/project/webform/issues/2473315