Formula Tool Calculations not Flowing Through Output

[Richard_E_Welch]

I have a workflow that has run just fine for the last couple of years until this month.  It appears that a Formula tool is calculating the formula expressions within it, but is not passing those values through the output.  When I copy the 2 tools of this processing flow to a new workflow and run it, the expressions are passing through the output.  This is a mystery I've never encountered before. I even tried deleting the 2 processing flow tools from the original workflow, copy the ones that worked in the 'temp' workflow, pasted them into the original workflow, and go the same issue when I ran the original workflow again.   Does anyone have an idea of what's going on and if there's a resolution for the workflow?

[alexnajm]

Does your Text Input have data?

[Carolyn]

Can you attach the "Error Sleuthing" workflow? 

[Richard_E_Welch · Accepted solution]

Unfortunately, I can't attached the workflow.  Yes, the Text Input has data.

I was able to determine the issue.  There was a Formula tool downstream with a field in a calculation expression that wasn't showing as existing because it was part of a monthly input sheet elsewhere in the workflow and that sheet happened to be blank this month, i.e., contained no data rows, just field names.  Once I created logic for what to do if that input sheet is blank, the initial issue was resolved.

Hopefully this helps someone else resolve a similar issue down the road!   : - )