NPE in schema changes model creator - create (55).

I added a custom column in an EC and when I run a 'changes only' build, I am encountering the following error :

NPE in schema changes model creator - create (55).

Why am I getting this error message and how do I move past it so my EC will build successfully? 

Note: In the past, I had another EC have the same issue and I ended up deleting the old EC and recreated the exact same cube. The build ran successfully. I could delete and replicate the EC because I did not have many visualizations referencing the cube. However, in case of EC build failure this time, I could impact a lot of exiting reports if I were to delete the EC .