Hello Dylan,
Thank you for reaching out about the issue with the “To” field not autocompleting in Outlook New and Outlook Web App. I understand how inconvenient this can be especially when you rely on this feature for quick email composition.
This behavior is not uncommon and can occur due to several reasons such as the AutoComplete feature being disabled, a corrupted cache, outdated Outlook versions or browser-specific issues.
Since you’ve already cleared the cache for both the app and the browser the next steps would be to confirm that AutoComplete is enabled in Outlook settings, update Outlook and OWA to the latest version and test in a different browser to rule out compatibility problems. If the issue persists it may be related to a recent update and contacting Microsoft Support would be the best way to check for known bugs and get tailored assistance.
Could you let me know if the AutoComplete option is currently enabled in your Outlook settings?
I hope this answer is helpful if you have further questions feel free to reply back
Regards,
Marcelo