Interesting, maybe a clue;
Could not remove files:
rm: cannot remove ‘/opt/librenms/rrd//ping-perf.rrd’: Permission denied
rm: cannot remove ‘/opt/librenms/rrd//poller-perf.rrd’: Permission denied
Removed device
So it removed it, but the other files had issues.
Yep. Re-adding the host from the gui is a non-starter.