I literally changed the values on the normal config and I found that some items do not stack. Like "Wood", "Stones", "Sulfur Ore"

 

Merged post

Getting the following errors as well when I try reloading the plugin:

Failed to call hook 'OnServerInitialized' on plugin 'StackSizeController v1.9.9' (InvalidCastException: Specified cast is not valid.)
  at Oxide.Plugins.StackSizeController.OnServerInitialized () [0x0012c] in <5336449a93f744cfa4155db61d9ec0e7>:0
  at Oxide.Plugins.StackSizeController.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00038] in <5336449a93f744cfa4155db61d9ec0e7>:0
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <9affce1cd15c4ec183941adef8db1722>:0
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <4452f821def6406d834e4149849fe7ea>:0
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <4452f821def6406d834e4149849fe7ea>:0