Calc- change date format

Using the standard dd/mm/yy, is no problem, however if I add dates /data later, then use either the Sort or filter controls the dates are in the wrong order , as it formats dates as text, not dates format

On a ‘clean’ spreadsheet this is no problem, same as format e.g. yyyy-mmm-yyyy - perfect , not when you add dates /data at a later stage. Advice please

Example document as .ods please.
Version, UI language, locale settings (date acceptance patterns e.g.) please.

...

???

Keep your eyes open and esure to do proper input/import.
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For input check first “date acceptance patterns”
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When importing data you can set the type of columns, so dates are imported not as text, but as proper dates.