arp2#branched sometimes has no neighbors in example actin model

## Description
When running analysis of actin outputs, arp2#branched sometimes has no neighbors found, even though it shouldn't exist with that type name if it does not have neighbors. Some instability at arp2/3 junctions is also visible in the outputs.

## Expected Behavior
arp2#branched particles should always have neighbors

## Reproduction
TODO
