Some of our users have reported receiving an "Invalid argument: timeZone. Should be of type: String " error when trying to merge events with their calendars. This is caused by a mismatch in timezones between the spreadsheet and the calendar you are trying to sync with. To fix this, you will need to manually change the timezone settings on each to match. Please note that Google does not list the same timezone options for each of their applications, so you may have to choose a different city than yours that has the same timezone.
To change the timezone on a Google Sheet, Click on File > Spreadsheet Settings.
To change the timezone on a Google Calendar, Click on the 3 dots next to the name of your calendar > Settings and Sharing.