Hi @Anonymous,
Thank you for sharing this.
I have tried to reproduce the error report with an example file but the "Extend" function worked fine.
It would be great, if you could share your mesh file that I can reproduce exactly what you have done?
I have checked the CER in our system and I could see that your Lenovo P70 Thinkpad / 20ERCTO1WW
is using the Intel HD Graphics card for Fusion 360. I assume that Fusion 360 should be running fine with the integrated NVIDIA graphics chip.
1. Could you may update the NVIDIA Optimus Display Driver with the link here
http://support.lenovo.com/us/en/products/Laptops-and-netbooks/ThinkPad-P-Series-laptops/ThinkPad-P70...
2. Could you may check your system for any driver updates with the link here:
http://support.lenovo.com/us/en/products/Laptops-and-netbooks/ThinkPad-P-Series-laptops/ThinkPad-P70...
3. It would be great if you could share a screenshot of your "Graphics Diagnostics" window, which should show the NVIDIA GPU.

4. Could you may share the system information with us? Here is an article which guides you through the process how to manually export the *.nfo file.
https://knowledge.autodesk.com/search-result/caas/sfdcarticles/sfdcarticles/Obtaining-system-informa...
I hope this helps. Please, keep us updated.
Thanks,