DAX comparison operations do not support comparing values of type Integer with values of type Text.

Hi timward10 
"" is a "white space" in which the data type is a text...
Try to modify the formula to 
Column = if(isblank(or('Opps+Products - Revenue Probability'[Contract Length (months)]),'Opps+Products - Revenue Probability'[Contract Length (months)]=0),12,'Opps+Products - Revenue Probability'[Contract Length (months)])
OR
Column = if(or('Opps+Products - Revenue Probability'[Contract Length (months)]=blank(),'Opps+Products - Revenue Probability'[Contract Length (months)]=0),12,'Opps+Products - Revenue Probability'[Contract Length (months)])
if it won't work 

Please share sample data (excluding sensitive information) in text format, along with your expected result and any relevant logic. For guidance, refer to

How to provide sample data in the Power BI Forum

If possible, upload a simplified .pbix file using this guide:

 How to upload PBI in Community