What does missing here mean?

[kavyagp]

I'm just trying to figure out if the column AsofDate is being populated from the source system or is built in alteryx by present date?

[CharlieS · Accepted solution]

The "(Missing)" label there means that field was previously included in the datastream, but was missing from the last time the workflow was run. Look at the tools upstream from there to discover the source of that field. 

Unless you removed the formula that created that field, this usually happens when that field is removed from an input source.

[kavyagp]

Oh Okay makes sense. That particular field has been used as the key to join tables. If it is missing from the source, the table joins make no sense.