Why is my bulk issue import from CSV failing to assign Parent Id?

[Davis Whitehead]

2020-05-08 15:57:51,198 INFO - Importer started!
2020-05-08 15:57:51,203 INFO - Engine is running in Import mode
2020-05-08 15:57:51,304 INFO - All issues will be imported to project: Tools (TOOLS)
2020-05-08 15:57:51,318 WARN - Issue 'Summary test' doesn't have Subtask Issue Type, its Parent Id mapping will be ignored.
2020-05-08 15:57:51,322 INFO - Creating issue: [externalId='autoid--1918449129747493097', summary='Summary test']
2020-05-08 15:57:51,549 INFO - Issue created successfully with Key [TOOLS-568], [externalId='autoid--1918449129747493097', summary='Summary test']

[Davis Whitehead]

There's no option for Subtask Issue Type in the available mappings: