Hi,
we have the same problem.
An admin tried to upgrade (single target) with right click

(22:27:07) | Calling 'OnPlayerInput' on 'Build v2.2.2' took 9294ms
(22:27:07) | Calling 'OnPlayerInput' on 'Build v2.2.2' took average 7ms
(22:27:16) | Failed to call hook 'OnPlayerInput' on plugin 'Build v2.2.2' (InvalidCastException: Specified cast is not valid.)
  at Oxide.Plugins.Build.DoGrade (Oxide.Plugins.Build+PlayerBuild buildplayer, BasePlayer player, UnityEngine.Collider baseentity) [0x00071] in <ff26768d59bd428fa23d50519634a567>:0 
  at Oxide.Plugins.Build+PlayerBuild.Execute () [0x001a5] in <ff26768d59bd428fa23d50519634a567>:0 
  at Oxide.Plugins.Build.OnPlayerInput (BasePlayer player, InputState state) [0x0013d] in <ff26768d59bd428fa23d50519634a567>:0 
  at Oxide.Plugins.Build.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000fd] in <ff26768d59bd428fa23d50519634a567>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <cc99cb05b42e4ea494cdf294badea406>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <99d545163fdd4d57a562df7989f2ca0a>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <99d545163fdd4d57a562df7989f2ca0a>:0
(22:27:16) | Calling 'OnPlayerInput' on 'Build v2.2.2' took 9320ms​

It consumed so much time that every player was kicked with packet flood :(