o.reload Tebex
Tebex was compiled successfully in 908ms
Unloaded plugin Tebex v2.0.5 by Tebex
Web request produced exception (Url: https://plugin.tebex.io/events) (NullReferenceException: Object reference not set to an instance of an object)
at Oxide.Core.Libraries.WebRequests+WebRequest.<WaitForResponse>b__40_0 (System.IAsyncResult res) [0x00000] in <18d4f19bbc844191b11ed9e69284d09b>:0
Loaded plugin Tebex v2.0.6 by Tebex

Search in the forums here about tebex. It would surprise you how much people left them. 

Hey there, try enabling debug mode with tebex.debug on, then run a force check with tebex.forcecheck. This should print any relevant web requests and errors to your server log. Please post them here and we can get a better idea of what may be going on.