Hey everyone,
sorry for reviving this old topic, but I feel like this can save you some hours of work if you run into the same problem. I've been using an increased sight range and found out that it can lead into visual bugs where objects are displayed at areas where they shouldn't be. At first I thought this was because of a ****** up Map.pk2/Data.pk2 but the error persisted even when using a clean Map and Data. However, the error disappeared when I used a client without patched background sight range.
Here's what this bug looks like, for a better understanding what I'm talking about.
I did use a background sight range of 10000, not sure if there's any threshold at which this bug appears.