Does not work with Javascript Maps

I am using a javacript map to store data I retrieve from an api for a udacity project.

However, the data is not being saved to the immutable object.

here is a branch you can clone and verify:

1. clone https://github.com/noahehall/udacity-trainschedule/tree/serviceworkers
2. npm install
3. npm run start

here is picture of implementation

here is picture of error received from immutable error TypeError: immutableDoesNotWorkWithJavascriptMaps.data.has is not a function(…)

Is there a workaround to get immutable to use Javascript maps? am i doing something wrong (very likely...)? or should I abandon seamless immutable?