Serial interfaces not showing traffic graphs

i have some Cisco an Adtran routers using serial interfaces (ppp over ds1 and ds3) and none of them show traffic on the graphs. they all show traffic when i use the real time option though. the data files for rrd exist and all other interfaces graph correctly.

i would like to retire my old observium install but it’s fairly important that i can monitor these links.


Component Version
LibreNMS 1.39-82-g1a618d0
DB Schema 251
PHP 7.0.28-0ubuntu0.16.04.1
MySQL 10.0.34-MariaDB-0ubuntu0.16.04.1
RRDTool 1.5.5

[OK] Composer Version: 1.6.5
[OK] Dependencies up-to-date.
[OK] Database connection successful
[OK] Database schema correct

A guess:
Have you checked to see if a bad_if is matching it?