Maintenance for the week of November 18:
• PC/Mac: No maintenance – November 18
• ESO Store and Account System for maintenance – November 19, 9:00AM EST (14:00 UTC) - 6:00PM EST (23:00 UTC)
• PlayStation®: EU megaserver for maintenance – November 19, 23:00 UTC (6:00PM EST) - November 20, 17:00 UTC (12:00PM EST) https://forums.elderscrollsonline.com/en/discussion/668861
Are you both on the same platform? Meaning that you are both on either PC, XBox One, or PS4? If you are on XBox, and your friend is on PS4, you won't see them, as this game is not cross-platform.
Would likely be helpful for each of you to say exactly which platform you are on, and which server. I'm not the most tech savvy guy, but I am betting that knowing those details would help people give you suggestions to fix this.