Thanks! I tried it with two different "random phenotype" files, and gives the same results. Just for future reference, the whole command was:
R --file=PRSice_v1.25.R -q --args plink PRSice_v1.25/plink_1.9_linux_160914 base referencefile.txt target myplinkfile slower 0 sinc 0.01 supper 0.5 report.best.score.only F no.regression T report.individual.scores T covary F pheno.file randomphenotypes.txt
The final output (after automatic cleanup) was two files: PROFILES.nosex and PRSice_SCORES_AT_ALL_THRESHOLDS.txt.
Best,