I cannot change the spaces in-front/behind of paragraphs when they are numbered. Please see my screenshot for details.
Is this a bug? Or I am doing something not properly? Please discuss.
This behavior of Word is related to a setting which suppress the spacing between paragraphs "of the same format". Since these paragraphs are part of the same list, Word sees them as "having the same format".
(1) Highlight the list elements.
(2) Right-click on one of them and select "Paragraph".
(3) Uncheck the setting "Don't add space between paragraphs of the same style".
This should solve your problem.
"Add/Remove Space Before Paragraph" commands adds/removes spaces before all the numbered items or after all of them. If you want to open the spaces between numbers (etc. 1 and 2) you should use "Line spacing options..." dialog box. Under "Spacing" group you can find "Line Spacing" settings.