steps to reproduce:
# go here: https://metrics-staging.wmflabs.org/cohorts/upload
# type in test name and description
# set default project to **enwiki**
# paste this into usenames textarea:
* KLeduc (WMF), enwiki
# Check box **Expand cohort to all user’s accounts across projects (via CentralAuth)**
# 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:
# click **Create New Report**
# select the cohort you just uploaded
# select **Edits** as the report type
# leave all default values except check the box **Individual Results** in configure output section
# run report and download CSV
RESULT:
search for enwiki and you will not find it. It should be there.