Incorrect chords beaming

[Dominique Fober]

with this gmn code:

{
[  \clef<"g2"> \meter<"C"> 
   \staff<2> %\stemsDown 
   \oct<1> 
   \beamBegin:1 
   \staff<2> {c2/8, c3/8  } 
   \staff<1> {c2/8, c3/8  } 
   \staff<2> a2/8
   \beamEnd:1 
], 
[ \clef<"g2"> \meter<"C"> ] 
}
~~~~~~~~~~

[Arshia Cont]

Another example on this:

{
[  \clef<"f4"> \key<2> \stemsUp \beamBegin:1 {d-1/8, d0/8  } {d0/8, d1/8  } {c#0/8, c#1/8  } {c#-1/8, c#0/8  } \beamEnd:1 \beamBegin:1 {b-2/8, b-1/8  } {b-1/8, b0/8  } {a-1/8, a0/8  } {a-2/8, a-1/8  } \beamEnd:1 ]
}