Why aren't contacts appearing in a Campaign when the Program Exit Report shows them going there?

I have a program with several conditionals that routes a contact to a campaign based on their country. It works fine for some countries. However, contacts from other countries make it into the program, get routed correctly to the step that sends them to the campaign, but don't ever appear in the campaign for their country.

For example, I have a contact with the country code DEU. The Program Exit Report shows that the contact exited the program as expected in the step that sends them to the DEU campaign. But when I view the campaign Entry Report, the contact doesn't appear.