The default decimal separator key for South Africa is wrong.
South Africa uses dot notation and not comma notation.
Solution : Goto Tools, Options, Language Settings, Languages
Keep user interface Default - English USA
Change Local Settings from default to any country with dot separator
(I used Dzonghkha)
Then go down to Default Currency and change it back to ZAR.
And change your date settings back to Y-M-D;Y/M/D;M-D;M/D
Apply or Save and all is well!
(I did this on Libre Office 6.4.4)