Cluster analysis for a subgroup of the sample

#1
Hi,
I used latent Gold software to cluster ANES dataset and it identified 3 clusters. Then I split the dataset to two subgroups: nonvoters and voters. LG identified the same three clusters in the nonvoters group, but the voters subgroup didn't cluster at all. It run 2-7 clusters models, none was fit. It's odd especially since the nonvoters are the majority of the dataset.
What can explain these odd results? Any idea or explanations would be of great help.
Keren