As for the poller.log you send, the polling seems to work normally and its writting the RRDs correctly.
Im not sure what can be affecting your system to dont print values in your graphs
Update. Using Dispatcher service actually fixed the whole issue and im even using 1 minute polling and the graphic contains data now.
For some reason, the cron file i copied over
cp librenms.nonroot.cron /etc/cron.d/librenms
did not actually work. cron log shows the commands executing but no data were being sent to rrdtools.
Anyway i couldnt solve it but dispatcher fixed the whole issue