Interface clustering not working in NMR structures

[kumar-physics]

PDB ID : 2ku2 is an NMR structure with C7 symmetry. It has 7 equivalent interfaces starting from interface id 1 to 7. But its not clustering when "cluster similar interface" is enabled.

[kumar-physics]

Clustering works properly for the following pdb entries.

1ai0,1aiy,1aq5,1c17,1dt7,1eq8,1f6g,1f96,1iie,1j7h,1jq1,1jq2,1kat,1m7l,1mpe,1mq1,1mwn,1nyj,1olg,1olh,1p23,1pes,1pet,1pfm,1pfn,1qce,1qey,1rfo,1rso,1sae,1saf,1sak,1sal,1suy,1sv1,1txp,1vrc,1wcr,1y74,1y76,1zll,2a9h,2aiy,2beg,2ezo,2ezp,2fxp,2g46,2h35,2h95,2hyn,2j0z,2j10,2j11,2jo4,2jo5,2jtt
,2k03,2k04,2k05,2k1e,2k2f,2ka3,2kad,2kb1,2kbm,2kby,2kdc,2ki6,2kih,2kix,2kj1,2ko8,2kp8,2kqt,2kwd,2kwx,2kyv,2l0j,2l5x,2l9h,2ljb,2ljc,2lme,2lmn,2lmo,2lmp,2lmq,2lnq,2lp7,2lpz,2lrk,2lrl,2ly0,2lzs,2m32,2m3b,2m3g,2m49,2m4j,2m5k,2m5m,2m5n,2m6i,2m6x,2m6z,2m7w,2mak,2mex,2nnt,2oii,2p80,2rlf,2rp4,2wwv,2wy2,2xdf,3aiy,3sak,3zpk,4aiy,4by9,5aiy,