Page Faults metrics not showing up in mongodb_exporter results

We’re loving the mongodb_exporter for prometheus, and it’s giving us tons of useful metrics. However, some of them are showing up blank. Notably:

mongodb_mongod_extra_info_page_faults_total

I understand that this metric comes from the “extra_info” group, which is governed by the -groups.enabled option. However we are not passing this option so I assume the default should apply.

According to the docs here: https://www.percona.com/doc/percona-monitoring-and-management/section.exporter.mongodb.html the default is “asserts,durability,background_flushing,connections,extra_info,global_lock, index_counters,network,op_counters,op_counters_repl,memory,locks,metrics” which should include extra_info.

Any pointers?