Something like a follow-up of bug 124881.
1. Open attachment 133861 [details] from bug 108343 in Excel;
2. Change the name of the Data field (Values area in PivotTable Fields sidebar) from "Sum of Amount" to, say, "FooBar";
3. Save it in Excel;
4. Open it in current LO master;
5. Save as XLSX again;
6. Re-open in Excel.
The data field in the original XLSX is initially named "Sum of Amount" (default name automatically assigned by Excel on creation), changed to user-defined "FooBar". When imported to Calc, it's shown as "Sum - Amount". Prior to , Calc didn't export anything as the field's name; which allowed Excel (older than 2016) to re-construct the name *as default "Sum of Amount"*. After the said commit, Calc started to export empty string, forcing the name to be empty. With , it now exports a name *as generated by Calc*.
The problem is, Calc should read, use, and export the name as defined in original XLSX.
Mike Kaganski committed a patch related to this issue.
It has been pushed to "master":
tdf#124883: don't drop data field names on import
It will be available in 6.3.0.
The patch should be included in the daily builds available at
https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.