Created attachment 136550 [details] Date scale x-axis with gap If in a chart with x-axis set to date scale a series value does not have a corresponding date, then LibreOffice assumes, that the date is 0. That results in ugly charts. It would be better, if the data point is skipped, same as Excel does it. The attachment has a screenshot, how the chart looks in Excel. It is not an import problem. You get the same ugly chart, if you generate the chart from scratch.
Reproducible. Version: 6.0.0.0.alpha0+ Build ID: 83288332f7ced698610739419989c464256f1c4d CPU threads: 4; OS: Windows 6.19; UI render: default; Locale: es-ES (es_ES); Calc: CL But please take a look saving the file as xlsx with LibreOffice and reload. Date's column lose the width but the chart looks nice. That's no happen saving as ods.
Created attachment 161268 [details] Screenshot of the document in current Calc This looks good since: https://cgit.freedesktop.org/libreoffice/core/commit/?id=55c5382591305a872b961d54571e3c823728ccb2 author Markus Mohrhard <markus.mohrhard@googlemail.com> 2018-11-29 19:11:58 +0100 committer Markus Mohrhard <markus.mohrhard@googlemail.com> 2018-11-30 13:17:27 +0100 tdf#42915, NaN in a date axis can destroy the whole chart
*** This bug has been marked as a duplicate of bug 42915 ***