Maintenance for the week of April 15:
• [COMPLETE] ESO Store and Account System for maintenance – April 16, 8:00AM EDT (12:00 UTC) - 6:00PM EDT (22:00 UTC)
Might be an add-on blocking making the potion or something because you don't know the traits... but it saying "Unknown" just means you don't know all the traits yet (which shouldn't preclude you from making the potion)