Photoshop 2020 Mouse Unresponsive on macOS High Sierra 10.13.6

I am running Photoshop 2020, latest update, on a Mac running High Sierra 10.13.6.  I am processing small (20-50 mb) files using two actions that I have used for quite some time with different iterations of Photoshop.  At random intervals photoshops stops responding to mouse commands - moving layers, selecting different tools, while still responding to keyboard commands.  I have deselected the GPU processor and increased the RAM to 85%.  If I quit and restart everything works until it doesn't.  Any ideas?

Thanks

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