Bizarre one this!
MBAir running 10.11.4 - Affinity 1.4.1
Using the Perspective Live Filter to correct an image, which works as expected. Set to Show Grid to get the Verticals correct.
Then use a duplicate screen layer to lighten the building and for some reason the grid lines are retained onto the picture when exporting or saving back into Lightroom. See the attached screen grabs and exported JPEG showing grid lines on and off depending on the screen layers visibility. Look at the cyclists at the bottom centre of the frame on the JPEG to see lines clearly.
Edited to add, when opacity is set to 100%, the lines are not visible, but when set lower, the lines become visible
Any ideas?