In the current version of the DATEX Tool, multiplicities and enumeration literals can be modified according to the rules of DATEX II 2.1, but these changes don't have any effect on the resulting schema (i.e. all literals are present, multiplicities are unchanged).
This was a strange bug. Or probablt it was a misstake done when merging braches with the trunk.
Some more testing tomorrow and then we probably can release it very soon.
Will be in version 2.1.4563 of the tool.