LMR

I don’t think the user is helped by Affinity Photo’s inconsistent handling of this requirement. Sometimes the selected layer is rasterized automatically, sometimes a pixel layer is added on top, sometimes the user is informed that a raster layer is required for the chosen operation, and other times (as in the case of the Inpainting Brush Tool) nothing happens at all.

Everybody makes that mistake - some of us still do!

Hi LMR
Welcome to the forums
please could you make sure you have your image layer selected then right click the layer and choose rasterise? This should make the tool work for you
Thanks
Callum

Make sure it's a pixel layer you're working on