enum switch: multiple members in one case not working

Hello, I would like to use the enum switch feature of MPS. I want to define more than one members per switch case. It should be possible to select multiple EnumMemberReference in the members child of EnumSwitchCase. However, the problem is that after I type a comma, I cannot input anything in the "no decl" space, there is no code completion and referencing (emphasis mine).

enum switch (link.sourceCardinality) { 
  _0__1, _1 -> { 
    cellCollection.childCellModel.add(< % ^( link )^ %>); 
  } 
  _0__n, <no decl> -> { 
    cellCollection.childCellModel.add(< (> % ^( link )^ % /empty cell: <default> <)>); 
  } 
};

Error message:

"No reference in the obligatory role 'decl'"

I reckon the culprit is the "heuristics" of reference nodes discussed in https://mps-support.jetbrains.com/hc/en-us/community/posts/206614295-Menus-Ctrl-Space- 

Is there a workaround? Do we need to report this as a bug?