Excel Writer parallel sheet appending fails - File locked issue?

Hello,

I have a big query that return a result that is fed into several pivots, then Excel Writer nodes which append a workbook with new uniquely named sheets.

When i run the flow, if i set all the sheets to overwrite existing sheet with same name, it shows as running correctly, but only the first sheet is included in the workbook.

If i set it to fail, about half the sheets work, and the rest fail saying already exists.

If i run one Excel Writer at a time it works fine.