Hi PhilipShek,
Thank you for querying in this forum.
From your description, it seems that you cannot find Chart element in Excel for 365.
If so, we have tested it with the latest version of Excel 16.49, we just created a new chart, when we clicked on Chart, we also cannot see Add Chart element icon, however, we can select the chart > click Chart Design tab > Add Chart Element, as shown below:

If you tried the way above and still cannot find Add Chart Element, to better understand your situation, could you provide the information below?
- Could you provide the version of your Excel? You can go to Excel > About Excel and provide the screenshot of it.
- Could you provide the version of Mac OS?
- Could you provide the screenshot of Chart Design? May I know if all files have the same problem?
Best Regards,
Sukie