A cross reference formula that was working before suddenly stopped working

iyengapr

I maintain a weekly project tracking system across two sheets:

Sheet 1 (Project Status):

• Contains detailed project status updates
• Adds 20 new rows each week (one per project)
• Includes a 'Snapshot Date' column to identify the week

Sheet 2 (Status Summary):

• Tracks project status counts (on-track/off-track) by week
• Previously used this formula to automatically pull unique snapshot dates:=IFERROR(INDEX(DISTINCT({Cross-Sheet Range}), [Row ID]@row , 1), "")

The formula worked successfully for a year but has recently stopped functioning. The cross-sheet reference no longer works as expected.

Has anyone encountered a similar issue or can suggest a solution?

Thanks in advance!

Paul Newcome

What exactly do you mean by it "no longer works as expected"? What is it doing vs what is it supposed to do?