Records processing through campaigns are not qualifying for the correct choice within the flow step logic and and are instead performing the default choice of do nothing.
To resolve this issue:
Verify that the value of the choice matched the value of the record at the time that it processed through the campaign.
Copy and paste the values from the choice step logic and the record detail in order to ensure that there are not additional characters that would prevent the record from qualifying for the choice. Even a small difference, such as a typo, will cause a choice step to skip.