Incomplete timesteps in gmx clustsize output

GROMACS version: 2018
GROMACS modification: Yes/No

I tried the clustsize command as shown below.

gmx_mpi clustsize -f …/polymer.nojump.mol.xtc -n polymer.ndx -s polymer.tpr -mol yes -cut 0.35 -pbc yes

At the end of the analysis, I found out that not all the timeframes were not written out in the avclust.xvg when compared to the nclust.xvg file. Please advise on appropriate solution to correct the anomaly (if any).