PowerApps form doesn’t save external data to SharePoint list

I’ve created custom form with PowerApps so when you click on New button in SharePoint you will see this:

This form is for SharePoint list Workflow but for column CostCenter I’m using external list Companies and Cost Centers where I’m filtering values based on selected Company (Cascading Dropdown).

I’m able to select data in those two fields correctly but when I hit the Save button in the form the value of CostCenter is not saved to Workflow list but everything else is.

So Title, Property Manager, Company, etc. except CostCenter is saved. I guess it’s connected to that Data Source of each field but I don’t know how to send those data from CostCenter to Workflow too.

Thank you for your help.