Image marks, number badges, and the mark-up tools (circles, boxes, arrows, notes) draw real Excel shapes, which needs the Shapes API: available in Microsoft 365, Excel 2021 and later, and Excel on the web.
If you see the message #
- On a perpetual Office older than 2021, shapes simply do not exist for add-ins. Everything text-based still works: the full mark library, the color emoji marks (which read like icons), sign-offs, steps as text, remove, highlight, the legend, and the open-items report.
- On Microsoft 365, the message usually means Office has not updated in a long time: File > Account > Update Options > Update Now, then restart Excel.
A quick alternative #
The emoji marks (✅ ❌ ⚠️ 🚩 and friends) render in full color in every supported Excel and behave like normal cell text: they sort, filter, and even attach to values. On an older host they are the closest thing to image marks, with none of the requirements.