I am following Blender Guru's Anvil tutorial on youtube however when I try to create a texture for a brush, the preview for the texture in the properties editor does not display the selected texture (clouds), see the image. Instead, the preview remains grey. The brush does paint with the selected texture.
I was stuck with this issue for a while. For me it was because I had my render engine set as Workbench, instead of Cycles or Eevee. Setting the render engine to something other than Workbench fixed the issue and the texture preview started showing again.