I have added a new object and data from Salesforce to Marketing cloud in data sources and it has synced. When I go to create a new journey, the object is there but not the fields. Am I missing a step?
Check that this object is properly synchronised and all the fields you want, have been selected to be synchronised as well.
Navigate to Contact Builder > Data Sources > Synchronised.
If the object is set up properly and it doesn't show you any synch-errors, double check the Synchronised Data Extension in Email Studio.
Navigate to Email Studio > Subscribers tab > Synchronised Data Extensions.
Check if the object you're having this issue exists there and all the fields you have chosen are visible Data Extension attributes.
If these two are all correct and you are still not able to see your object under the
Contact Data path, you may want to double-check that the object is correctly linked to Contact object (or directly linked to it)