In brief
In flex layout, justify-content distributes remaining space along the main axis. If growing items already consumed that space, space-between may have no visible room left to distribute.
Useful to know
In flex layout, justify-content distributes remaining space along the main axis. If growing items already consumed that space, space-between may have no visible room left to distribute. [1]
When alignment seems inactive, inspect container size and child flex-grow values. Establish whether free space exists before adding further spacing rules.
Sources
For further detail and to check the information: