Substract time columns from diff datasets

Hi LearnerMM 

Thanks for clarifying. If Power BI isn’t letting you select columns across datasets, it’s likely due to how the model is set up especially if you're using a composite model (Import + DirectQuery) or separate sources without an active relationship.

If Table1[EST] is the scheduled time and Table2[EST Start] is the actual time, and there's a one-to-many relationship from Table1 to Table2, you can write a calculated column in Table2 like this:

DelayMinutes = 
DATEDIFF(
    RELATED(Table1[EST]), 
    Table2[EST Start], 
    MINUTE
)

Double-check your relationship direction in the model view. Make sure you’re referencing from the correct side (many side → one side) when using RELATED(). If you're using different sources, consider merging them in Power Query or creating a bridge table with shared keys.