Hi, thank you for your question. Here are some possible solutions you can try.
Check Office Version:
Ensure that you are using a version of Microsoft Office that supports the Icons feature. This feature is available in Microsoft 365 and Office 2019.
Check for Updates:
Make sure that your Microsoft Office suite is up to date. Open PowerPoint and go to "File" > "Account" > "Update Options" > "Update Now."
Customize the Ribbon:
To customize the ribbon, please try to do Right-click on the ribbon and select "Customize the Ribbon." In the right column, ensure that the "Insert" tab is selected.
Look for "Icons" in the left column and make sure it is selected. and Click "New Group" to add a new group to the Insert tab if needed. Click "OK" to save changes.
I hope this helps. if it works for you, please let me know by marking this thread as "answer".
Let me know if you have any other questions.