Curves Adjustment not working Affinity Photo 1.9 (Windows)

[Harleyman]

I can create a node on the curves adjustment "line", but I cannot move the line into, say, an S curve.  The node and line won't move.  This has only happened with version 1.9.

I'm on a Windows platform with i7 processor, 16GB RAM, and nVidia Geforce GT640 with 2GB VRAM.

[ashf]

Try to turn off Hardware Acceleration in Preferences>Performance.

[Harleyman]

Hardware acceleration wasn't activated.  I also tried it using the Windows renderer instead of the Geforce GPU.  Still no good.  Should I go back to the previous version of Affinity Photo?  Keyboard cursor keys (arrows) move the points just fine.  Mouse and pen/tablet do not.