Why doesn’t the app recognize my mouse/trackpad’s clicks? 

If you’re using iPadOS 14, then your iPad’s Accessibility settings are the culprit. 

Make sure that you don’t have both AssistiveTouch and Perform Touch Gestures switched on. If you turn on the latter and use a pointer device (mouse or trackpad), that means apps such as Shapr3D recognize pointer clicks as taps. This can be problematic if you already have AssistiveTouch enabled—Shapr3D will not be able to differentiate between taps and clicks. 

You can use the Apple Pencil to avoid this problem. But, you can fix the problem in a few steps: 

1. Open your iPad’s Settings app. 
2. Go to Accessibility > Physical and motor > Touch > AssistiveTouch.
3. Switch off either AssistiveTouch or Perform Touch Gestures. 
   

I’m using the macOS beta. What do I do if the trackpad won’t recognize pinches as a zoom gesture?

1. Open System Preferences > Trackpad. 
2. Select the Scroll & Zoom tab.
3. Mark the Zoom in or out checkbox.