I have reviewed many of the articles regarding this subject and none have provided resolution.
Background:
Board type: Scrum
Project version: Classic
Project location: https://digicomm.jira.com/
Board view: Active Sprint
Board Query:
project = labkey AND issuetype in (story, Bug, Subtask) AND (cf[23773] = PortKey OR cf[23774] = PortKey OR cf[23775] = PortKey) OR project = "Digital Data Repository" AND issuetype in (story, bug, Subtask) AND (cf[23773] = PortKey OR cf[23774] = PortKey OR cf[23775] = PortKey) OR project = Portkey ORDER BY cf[14010] ASC
Offending Story in project: Digital Data Repository
Offending Story project version: next-gen
Subtask status: todo (which is mapped to column in board)
Running the query shows the subtasks.
Subtask does not show on board