Hello @JW63
If you are still having issues, and everything else is syncing to Google besides the events you created manually, you may need to speak with Canvas support or your school IT help desk directly. Other assignments from the courses sync? Even new ones added? If some of them work, and some of them don't there may be an underlying issue or something causing this.
Because of the complexity of the issue, and the concerns for privacy, it would be best if you contacted Canvas Support directly to pinpoint the source of the issue and provide a resolution:
https://community.canvaslms.com/t5/Canvas-Basics-Guide/How-do-I-contact-Canvas-Support/ta-p/389767