In Word, the envelope feature normally works through Mailings > Envelopes, where you enter the delivery and return address, then select Add to Document or Print. If the icon isn’t responding, it may be caused by an add-in conflict, a corrupted template or Word running in compatibility mode. Are you getting no response at all when clicking the Envelopes icon, or does a window open but not print?
Try these steps:
- Close Word, then press Windows + R, type winword /safe, and press Enter. Try the Mailings > Envelopes button again. If it works here, an add-in is likely causing the issue.
- Go to Settings > Apps > Installed apps > Microsoft 365 > Modify > Quick Repair. This often fixes broken buttons or templates.
- Open a blank document, go to Layout > Size and choose your envelope size, then place your addresses using text boxes to print. This works as a workaround.
More info here https://support.microsoft.com/en-us/office/print-envelopes-efcb63be-226c-4541-8b9b-8e316da670ed.