Decimal values in chart data editor

Possible solution:

Numbers:

Click on " View" on the top of the screen. Click " show format bar". When the bar is shown, look at the middle of that bar. If correct you see 1,0 Euro or dollar, % and V. To the right of it you see a downward arrow. Click this and select custom. You're shown a screen "type text and drag ....." You can change date but also number and text.

Look at the definition of the decimals. If correct you must see a komma and 2 digits.

Apple preferences:

If this doesn't work go to system preferences of Apple. Select language and text. Make your corrections there (in formats)

Good Luck.

Works the same with Keynote.

Select format, select chart, select axes. The selected format must be numbers.

Again look at your apple preferences.

It works fine with me, even below 24.

Apple preferences: check not only your language (you already did) but also your format. Is must allow komma,

Well, problem solved for now I think.