XLSM unable to be saved
The attached xlsm fails to save when read in with vba preserved. It doesn't remove VBA, it literally won't save the file again. I believe this is a byproduct of either formatting or buttons in the sheet but haven't been able to track it further, and in this instance it means that even my simplistic task of adding a few values to the main sheet is impossible without the workbook being simplified or corrupted. I've tried to track down what's going on here but it's shown itself to be too complex for me, so I'm submitting an anonymized version of the sheet for replication purposes.
Hmm, I seem to be unable to upload the file here, so I've zipped it up and uploaded it to a corresponding issue at https://github.com/chronossc/openpyxl/issues/66 instead. It's available for download/testing there.