Why are ods chart data ranges changing to data tables?

I see that there are other posts about this; of the posts I have read, none provide a firm explanation or solution for this behaviour. Charts established by assigning data ranges in Calc (ods) are changing to data tables randomly (it seems) without user action. In a workbook of several worksheets and numerous charts, not all the charts have converted so far, but more and more charts are changing as I continue to use the spreadsheet. When this happens, charts lose their connections to their original data ranges. I am not converting from other file types or applications, and am not copying and pasting charts. As described elsewhere, the “Data Table…” option appears unexpectedly in the right-click menu, and the “Data Ranges…” dialog explains that the Data Table is present and that one can replace the Table with Data Ranges. Is there a solution for this? Thank you.
Using Version: 6.4.3.2 (x64)
Build ID: 747b5d0ebf89f41c860ec2a39efd7cb15b54f2d8.

(You are using Excel terms:) Did (do) you save in-between to alien file formats (.xls, .xlsx of any version)?
I never do so, and I never observed a “randomly changing” of Chart from the DataRanges to the DataTable version.
User interaction like Cut/Paste a chart elsewhere and later Copy/Paste it back may cause such a change, of course. After all the chart needs to keep its data if range access inside the document no longer is possible. Recent versions of LibO Calc offer re-establishing the binding to ranges in this case. Binding to external data still is not supported.

Side note: binding to external data is supported if the data range is entered as an external reference

'file:///home/user/Documents/name.ods'#$Sheet1.$A$1:$A$5

Interesting.
However, I don’t know a way to bind a Chart inserted into a text document this way. This even if the chart was copied from a spreadsheet document and already set there to the external DataRanges.

Ah no, that doesn’t work because the chart asks the data provider of the embedding document and Writer doesn’t know anything about Calc’s reference syntax. I don’t know if Writer can reference external documents’ tables, but I doubt it. As soon as a chart is copied from Calc and pasted elsewhere the data is carried along as a Chart internal data table, unless chart and data are copy-pasted together copying the entire sheet(s) to another Calc document.

Back to the question, @wjc001 did you save the file as Flat ODF document .fods at some point in time? I slightly remember a bug with chart references turning into internal data tables in some circumstances there.

Thank you erAck and Lupp. I used Excel for many years and started using LibO about two years ago; hence the Excel terminology. To erAck… I appreciate the external binding info – I’ve used this in excel and will try it in Calc – I had been wondering about it but not yet done the research. To answer your questions… The spreadsheet in question was established in Calc and never saved to any alien type. I have duplicated charts on the same worksheet and then changed the DataRanges, in order to copy the Chart formatting. New idea: Occasionally LibO needs to “recover” files for some reason I do not understand. This recovery is always successful, but could that process lose the DataRanges and convert to DataTables version if there are unsaved changes? I’ll experiment with this and report back. Thank you both, and best regards.

I am having the same issue. Making me crazy. It seems to happen once the spreadsheets get over a certain size.

My last post mentioned this: “Occasionally LibO needs to “recover” files for some reason I do not understand. This recovery is always successful, but could that process lose the DataRanges and convert to DataTables version if there are unsaved changes?” Since then LibO has not needed to “recover” files, and I have had no more changes to DataTables. I have also been careful to save files after every editing session, and to never save any file while a chart is selected for editing.