I have the Enterprise plan that allows me to upload 50,000 names. I have a file of 49,000 names and when I try to upload the file, I can select the file, and click continue, but it never gets to the mapping stage. I have tried to upload the file as XLSX and as CSV, but neither file gets to the mapping stage.
Thanks for reaching out to us via our Community! Sorry to hear that you are running into an issue loading your contacts. Have you tried to break the list down, so that you are only loading half of it? It sounds like the app may be timing out trying to upload all of this information. Give this a shot and let us know if this works for you. If you run into further issues I recommend chatting us or shooting us a note at: firstname.lastname@example.org.
Thanks for your time Larry and have a lovely week!