Like mentioned before... if you customize out of the box modules through PROTOTYPING and EXTENDING, upgrading isn't as bad as everyone makes it to be. If you just simply override out of the box modules, upgrading will be a nightmare.

For simple front end things that do not require ssp-library or service file updates, we usally run gulp local. When we need to deploy, we use deploy to our sandbox environemnt. If you do not have a sandbox, I recommend creating a development SSP Application and deploy your code there.

Sometimes this happens to me when I misspell an object in the ns.package.json file of the module. Ex: When I name my js folder JavaScript, but in the file the path is spelled Javascript

Not sure if this will help, but maybe you need to update your field sets to expose the fields you are using on the item details to the cart?

I ended up creating a suitelet to return the data I needed. Thanks for your input.

Can you please elaborate on the process for the alternative. Thanks.

I highly recommend using Git along with Sourcetree. Sourcetree has an awesome interface.

Hi Mariano, I opened up a case, #3051052. I believe support also filed a defect as well.