Some ONTs in the GPON Service chain topologies are being displayed as -1 values. These ONTs are most likely missing data from above fields that are not being aggregated properly or found unavailable. I'm hoping to learn which driver this data may be coming from BE/FE/collectors in order to make this accessible to the ONTs. If this is not possible, we would proceed by hiding the cells labeled as -1, however in the visibility topology tag it seems that only field visibility modifiable. I was wondering if it was possible to perform a conditional on the cells themselves on the EPM FE.
This issue also looks to be present at the network level.
Your assumption of the ONTs being missing data to map to the parent levels is likely correct as your scenario is very similar to the one described in the highlighted note of this page section allowValues/ignoreValues | aggregate.
I would start by checking if you are missing an ignoreValues option in your aggregate actions and I would also check your merge actions for the need for a limitresult | merge option as also described in the note of the first link.
As to which connector the issue may be originating, it is difficult to say but given that you are seeing the -1 value at the lower levels I do believe it is likely something you need to check in all of them as data comes from the lower levels from the collectors and gets aggregated to the upper levels first by the backend(s) and finally by the frontend.