Percona pmm agent Mongodb

I'm setting up percona pmm for mongodb but the agent is chewing a lot on cpu.

I have pmm-admin 1.5.0 on CentOS Linux release 7.2.1511 and Mongodb 3.0.12 and I see the /usr/local/percona/qan-agent/bin/percona-qan-agent using 100% constantly.

Doing an strace on a thread I do see

futex(0xab0de0, FUTEX_WAIT, 0, {0, 223304991}) = -1 ETIMEDOUT (Connection timed out) or read(8, 0xc4200839b0, 36) = -1 EAGAIN (Resource temporarily unavailable)

... though data shows up into the pmm/qan server.

I tried many configurations and the one that shows data is

--uri 'mongodb://host:port/?replicaSet=replicaName&authSource=admin',

I do have authentication enabled and a replica set.