Hey,
The team has fixed the CSV Uploading issue, so you should no longer experience this. If you do encounter it again, please reach out.
You can also try a hard refresh before uploading:
Mac:
• Chrome/Firefox: Press Cmd + Shift + R
• Safari: Press Cmd + Option + R
PC:
• Chrome/Firefox/Edge: Press Ctrl + F5
Let me know if there is anything else I can help with!