Hi James, This is Bryll
Thank you for writing us here in Microsoft Community.
As I have replicated on my Windows PC, Review > Start Inking works when a primary display is on presentation mode while the secondary display have the PowerPoint slides in editing mode. For your reference, please have a look here: Draw on slides during a presentation - Microsoft Support
If you are using a separate Tablet device to draw ink while presenting on your Windows PC, we can isolate the problem to determine if it is with PowerPoint application itself or a limitation from the Tablet device by either using PowerPoint on the web or using another Tablet device.
On a web browser, open PowerPoint online using this link PowerPoint | Microsoft 365
Once PowerPoint online is open, create a new PowerPoint presentation
After creating a test presentation, have it on presentation mode then try using Draw ink.
If problem persists, it should indicate that the problem is with limitation from the Tablet device which may have an outdated Android or iOS version since it produces same behavior to different platform of PowerPoint.
If you have a different Tablet device on hand, try using it to Draw ink to confirm if the same problem would occur. For the same, please consider in following the troubleshooting steps below:
1. Run PowerPoint in Safe mode: Press the Windows key + R on your keyboard to open the Run dialog box. Type powerpnt /safe in the Run dialog box. Press Enter or click OK. Once PowerPoint in safe mode is open, try creating a new presentation to test Draw ink.
2. Disable 3rd party Antivirus programs as it may be interfering with Microsoft Office and Windows services.
3. Repair Office suite: Go to Start menu Settings Apps Find your Microsoft Office suite version > Modify/Change > Quick Repair
4. Reinstall Office suite: Go to Start menu Settings Apps Find your Microsoft Office suite version > Modify/Change > Uninstall.
Important note: Make sure you have your product key or account information ready before you do this. You can download the Office setup file from your Microsoft account website Microsoft account | Services & subscriptions or use the media that came with your purchase.
Should problem remain, we would like to gather the details indicated below and please send us some screenshots if possible so we can recommend other strategies.
1. What is the version build and the email account on your PowerPoint? Go to File > Account > User Information and Product Information
2. What OS version your computer is running on? Type and open System Information from start menu
3. What is the Android/iOS version of your Tablet?
4. Are you using a work/school computer? If yes, is it managed or connected by a domain?
Kindly send us a reply if there is any misunderstanding or clarifications to our description.
Yours truly,
Bryll
Microsoft Moderator