Steps causing the bug to occur: 

ShaderToy has changed their syntax, so the Make Image with Shadertoy node needs to be updated (as noted on is there a way to realize a GreenScreen / Chroma Keying and ShaderToy GLSL node re-purpose).

Have you found a workaround?: 

Instructions for modifying newer Shadertoy code to work in Vuo, courtesy of @alexmitchellmus:

  • Change the void mainImage( out vec4 fragColor, in vec2 fragCoord ) function to void main() (no text in function brackets) some people do: void main(void) but it works in Vuo without.
  • Change FragColor (or) fragColor to gl_FragColor
  • Change FragCoord (or) fragCoord to gl_FragCoord