openpyxl destroys functions on save - openpyxl

Question

I'm trying to save pandas DF into an existing spreadsheet. I found an excellent answer at Writing Pandas DataFrame to Excel: How to auto-adjust column widths, which is really continuation of another question *)
The problem though is that when I use it, on trying to load the spreadsheet I get an error on "damaged content", complaining about a drawing - even though I have none in the spreadsheet, and all functions are gone. Static data are still there.
log is
<?xml version="1.0" encoding="UTF-8" standalone="true"?>
-<recoveryLog xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main">
<logFileName>error171360_05.xml</logFileName>
<summary>Errors were detected in file 'test.xlsx'</summary>
-<repairedRecords summary="Following is a list of repairs:">
<repairedRecord>Repaired Records: Drawing from /xl/drawings/drawing1.xml part (Drawing shape)</repairedRecord>
</repairedRecords>
</recoveryLog>
Any ideas?
Edit: I'm pretty sure now it's not caused by pandas, as opening workbook, adding an empty sheet, and saving it removes all the formulas.
workbook = load_workbook(file)
try:
sheet = workbook["Result"]
except KeyError:
sheet = workbook.create_sheet("Result")
# for r in dataframe_to_rows(result, index=False, header=True):
# sheet.append(r)
workbook.save(file)
It doesn't produce the error above though.
Edit2: There's a question from 2013 (Openpyxl: Formulas getting removed when saving file) which says OpenPyxl doesn't support it, with a feature requested to do so. But the link to the feature doesn't work, so I have no idea whether it works or not.
*) there is a small bug in the function in that answer, sheet_name is a param, but it also tries to look it up in **kwargs, which of course fails, so gets replaced by a default value even if passed into the function. I can't comment on the question, so maybe #maxU will read this and edit..