GMX dipoles autocorrelation function error

GROMACS version:
GROMACS modification: Yes/No

When running gmx dipoles with -corr mol the dipole autocorrelation function outputs nan for all values. The outputs of Mtot, Aver, and Epsilon seem to be fine, but the autocorrelation file is not being generated properly.

Alternatively, I could create a script to generate the autocorrelation function from the other output files. Is there any available information on how the dipole ACF is generated?