This wokred for me Teamveiwer version12: If you can see everything, but cannot control, try the following on the Mac you want to control: On the Mac that you want to control, go to System Preferences > Security > Privacy > Accessibility. Un-check the TeamViewer and TeamViewer_Desktop entries. Check the TeamViewer and TeamViewer_Desktop entries again. If you still cannot control the Mac and it has "Start with system" turned on: Turn "Start with system" off on the Mac you want to control (Remote Control > Unattended Access). Restart that Mac (just in case). Open TeamViewer again (still with "Start with system" off). Can you control that Mac now?
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