Created attachment 166912 [details] Chart with non automatic date axis Open attached document and verify these settings for the x-axis in the chart: Type Date Resolution Days Major interval 1 Month Minor interval 7 Days Save the file to xlsx format. Reopen. The settings are now Type Date Resolution Automatic Major interval Automatic Minor interval Automatic "Automatic" does not resolve to the original settings. Excel is able to use the manual settings and a chart with such manual settings made in Excel opens correctly in LibreOffice. Thus I think, it is an export error.
Created attachment 166916 [details] The better example file and its XLSX-saved version in Calc Confirming with Version: 7.1.0.0.alpha1+ (x64) Build ID: ec1f4d3253963ac16d638734ac70dde033e82154 CPU threads: 4; OS: Windows 6.3 Build 9600; UI render: Skia/Raster; VCL: win Locale: hu-HU (hu_HU); UI: en-US Calc: CL
Created attachment 166917 [details] The xlsx-export with manually setting same options in Excel 2013
Created attachment 166918 [details] The Excel-made file in Excel 2013 and Calc For comparison: the same options can be set in Excel and are correctly imported by Calc. So this is an export-only problem.
Balazs Varga committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/commit/e8a9d0050675034aa5d4670330ea47ef32306973 tdf#137917 Chart OOXML: fix export of TimeIncrement of Date axis It will be available in 7.1.0. 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: https://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.
*** Bug 138385 has been marked as a duplicate of this bug. ***
Verified in: Version: 7.2.0.0.alpha0+ (x64) Build ID: 368c56144aab5794c39d5bc2082d9b3d6d7cebdb CPU threads: 4; OS: Windows 10.0 Build 17134; UI render: Skia/Raster; VCL: win Locale: hu-HU (hu_HU); UI: hu-HU Calc: threaded Thanks for fixing!