Hey I just had to roll back to my old version I had, it seems after a while or if enough items are enabled, it stops drawing all elements on screen and produced chat message to check console for error.

The error:

(19:47:09) | [Admin Radar] Error @Active: Object reference not set to an instance of an object --- at Oxide.Plugins.AdminRadar+Radar.ShowActive () [0x00230] in <c41f447a74774ef4b8dd9c13f2954688>:0

it doesn't matter how many elements are being drawn at any given time.

the error specifies the issue. thanks for reporting it, it's fixed in 5.1.7