Clarifications needed for 'prompt' parameter of ios_command module

When i use ‘prompt’ parameter of ios_command module for IOS image copying as in Example 1, it fails. But it succeeds as in Example 2.
I want to understand why? I am trying to understand why this below syntax works?
Destination filename [ image name]?’

This issue happens only for IOS copying and not for other prompt related commands.

Example 1 (fails):
ios_command:
commands:

Example 2 (suceeds):
ios_command:
commands: