[Linux Mint Cinnamon][Krita 5.2.16] How do I permanently apply a filter mask to a layer?

I have a paint layer. I added a filter mask to hue shift the colors of that paint layer. I want to make the changes permanent and apply the filter layer to the paint layer.

I can right-click the filter layer and I can see "Merge with layer below" but it is grayed out. If I use "Convert to paint layer" the whole image seems to turn white, beyond just the paint layer.