Inconsistent Camera optimization

[Pulkit gera]

Im running a simple camera optimization code where the initial image optimizes to target scene. I run this script on

1. ubuntu 20, 2080Ti
2. colab instance with Tesla p100
   i get 2 different outputs where the ubuntu one isnt able to optimize it at all.
   Result in first case -
   
   Result in second case -
   
   Both run the latest version of pytorch(1.6.0) as well as redner(0.4.28)
   Both the files run the same code - https://colab.research.google.com/drive/1_gfTnvclHgIsNIRG8mJF_4TgJYPrfrXl?usp=sharing
   Please help. Need it for research work
   @BachiLi @tstullich