You may see this happen occasionally due to a couple factors affecting the display:

1. We only show links in the network visualization between the latest values.
2. We update user identifiers when they have activity, or when someone they're linked to with a high score has activity.

What this means for the network visualization is sometimes user identifiers will not have bi-directional links.

For example:

Let's say both User ID #1 and User ID #2 have recent activity with IP address 1.2.3.4. User ID #1 will see User ID #2 in their network and vice versa.

Then User ID #2 has new activity with IP address 5.6.7.8, but User ID #1 has no new activity. Now when you look at their visualizations, User ID #2 will no longer see User ID #1 in their network; however, User ID #1 will still have User ID #2 in their network (since we haven't updated them yet).