GPU acceleration does not appear to be working

[M Y]

It takes my PC 3 minutes and 28 seconds to smart sharpen one 16MP image. The CPU (Core i7-8700) runs at maximum peed during that time but the GPU (GeForce GTX 1050i) sits idle. I have made sure opencl is enabled. I've searched the forums and tried lots of suggestions. I've updated the drivers for the GPU. I've tried bsic, normal, and advanced drawing modes. Still no success. Any ideas? Thank you!