steps to reproduce:

1. go here: https://metrics-staging.wmflabs.org/cohorts/upload
2. type in test name and description
3. set default project to enwiki
4. paste this into usenames textarea:
   • KLeduc (WMF), enwiki
5. Check box Expand cohort to all user’s accounts across projects (via CentralAuth)
6. click Create Cohort

RESULT:
one entry is invalid, but all should be valid. I suspect "KLeduc (WMF), enwiki" is the invalid entry but I cannot tell from this screen. here's how I dig deeper:

1. click Create New Report
2. select the cohort you just uploaded
3. select Edits as the report type
4. leave all default values except check the box Individual Results in configure output section
5. run report and download CSV

RESULT:
search for enwiki and you will not find it. It should be there.