Question:

When converting a Lead to an Account there is an option to create an Opportunity as well. The problem we're having is that none of the information from the Lead is being set in the Opportunity(mainly the LeadSource) even though the fields are in both the Lead and the Opportunity.

Answer:

This is SalesLogix default behavior. 

You would need to change the code in Architect. You could create a global variable when the "InsertOpportunity" function is called and then populate the fields on the WhenOpen of the Insert Opportunity form