I gave up trying to get "Tasks" into the Planning board, JIRA is not configured that way. Lots of complaints from people on it (and I agree), but I gave up. Under Administration I created a new "Issue Type" called "Change Request_Task", and link those items to the "Change Request". Not exactly following convention, but how I decided to move ahead.
I'm not sure what your problem is but:
1) Issues have to be returned by the filter you use in a particular board - take a look at the filter / maybe you don't include "tasks"
2) the statuses the tasks are inhave to be mapped to the boards columns:
Hope you get it to work,
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