Hi asims, sorry for the delay. I've tested in 2018.2.15 and cannot reproduce the problem... because of that it's hard for me to say where the problem is 100%. BUT if I were to guess I would suggest opening the Scripts/TenkokuModule.cs file and making a code edit...
Around line 780 you'll see this line initiating a rendertexture:
_particleDensityLUT = new RenderTexture(1024, 1024, 0, RenderTextureFormat.RGFloat, RenderTextureReadWrite.Linear);
Ypu can try replacing the "0" with "16" like so...
_particleDensityLUT = new RenderTexture(1024, 1024, 16, RenderTextureFormat.RGFloat, RenderTextureReadWrite.Linear);
Then saving, going back to the unity editor and run your scene again. I'd be interested to know if this makes any difference on your end?