I've been experiencing this issue with Tripplite PDUs. The current sensor gets removed and added every few cycles. Or just gets removed and lost.
5h 24m 26s Status deleted: ups-mib-output-state upsOutputSource.0 Source of Output Power
5h 24m 26s Sensor deleted: current ups-mib upsOutputEntry.1 Output
1d 11h 18m Status added: ups-mib-output-state upsOutputSource.0 Source of Output Power
1d 11h 18m Sensor added: current ups-mib upsOutputEntry.1 Output
1d 11h 18m Input Sensor added: frequency ups-mib upsInputEntry.1 Input
1d 11h 18m Input Sensor added: voltage ups-mib upsInputEntry.1 Input
1d 17h 23m Status deleted: ups-mib-output-state upsOutputSource.0 Source of Output Power
1d 17h 23m Sensor deleted: frequency ups-mib upsInputEntry.1 Input
1d 17h 23m Sensor deleted: current ups-mib upsOutputEntry.1 Output
1d 17h 23m Sensor deleted: voltage ups-mib upsInputEntry.1 Input
Kyle - One small suggestion that I've done locally. Set your SNMP retries to a higher value, and your timeout to 90 seconds or more.
Ever since I've done that, I haven't had any of the sensors disappear.