Magma error: Could not find a covering group

Question

Let $G = PGL_{4}(5)$. I find an elementary abelian $2$-subgroup of rank $3$ denoted by L1[35] in the following code. Then I have Magma compute the centralizer and normalizer of this subgroup which are denoted by $C$ and $N$ below. Here $C\cong V_{4}\times D_8$. There is a cyclic subgroup of order $4$ in $D_8$ constructed as "qminus1" below. At last I construct the quotients of $C$ and $N$ by this "qminus1" which are denoted as "cq" and "nq" below.

My aim is to find the nq-conjugacy classes of cq. But Magma gives "Runtime error in 'Conjugates': Could not find a covering group"... Any help would be appreciated.

    G:=PGL(4,5);
    S1:=SylowSubgroup(G,2);
    s1:=ElementaryAbelianSubgroups(S1);
    L1:=[s1[i]`subgroup:i in [1..51]];

    C:=Centraliser(G,L1[35]);
    N:=Normaliser(G,L1[35]);
    C:=N!!C;

    E2:=DirectProduct(CyclicGroup(2),CyclicGroup(2));
    D8:=DihedralGroup(4);
    CQ, inj:=DirectProduct(D8,E2);
    D88:=Image(inj[1]);
    D88;

    flag,isom:=IsIsomorphic(CQ,C);

    Generators(D88);
    genset:=Generators(D88);
    gset:=SetToIndexedSet(genset);
    q:=gset[1]@isom;

    qminus1:=sub<C|q>;

    cq:=C/qminus1;
    nq:=N/qminus1;
    Conjugates(nq,Identity(cq));