[GAP Forum] ExtensionsByGroupNoCentre apparently misses groups

[Benjamin Sambale]

Dear Forum,

consider

G:=TransitiveGroup(20,543);

The following commands show that G is an extension of A5xA5 with C4xC2:

N:=First(NormalSubgroups(G),n->Size(n)=60^2);;
StructureDescription(N);
StructureDescription(G/N);

Since A5xA5 is perfect and centerless, G can be constructed via 
ExtensionsByGroupNoCentre from the grpconst package (according to the 
manual):

K:=Group((1,2,3),(3,4,5),(6,7,8),(8,9,10));;
H:=Group((1,2,3,4),(5,6));;

LoadPackage("grpconst");
ext:=ExtensionsByGroupNoCentre(K,H);;

However, G does not appear in the list of extensions:

List(ext,x->IsomorphismGroups(x,G));
[ fail, fail, fail, fail, fail, fail, fail, fail, fail, fail, fail, fail ]

Any thoughts? I'm using GAP 4.7.8.

Best wishes,
Benjamin