Hi Jake,
From your screenshots, it seems that the the email address of the calendar disappeared when you set your windows to High Contrast mode.
May I know if you select the high contrast theme as High Contrast Black? Please press Windows logo key + U to open
Ease of Access settings, then select High contrast, you should see the option "Select a colored rectangle to customize high contrast colors", please try to set as following to check the outcome:

If the issue persists after you tried as above, please provide us your Outlook version. (version and build number under Product Information)
Besides, may I know if it happens all the time (for all calendars) or occasionally?
Thanks,
Iry