We have a production problem with wrong sums.
Symptom: The sums are wrong. The sum formula contains cells for all sheets and all cells concatted with "+". This only happens if the collection (that contains data for all the sheets) has many items (326).
Target: The sum formula should contain only an area (e.g. "E2:E260") of the current sheet to produce a correct sum.
We found out that issue
#59 causes this problem. We guess it does not work with multisheets.
We subclassed the StandardFormulaProcessor and took back the change https://bitbucket.org/leonate/jxls/commits/70f3a70f2e21 . After that the sums are correct. However, this is not the final solution. But now our client can work again.
What are your plans to release a fixed version? :-)