FYI I have not touch anything in over 6 months as I've has no reason to so the config and any data files are untouched.
My Players are conplaining about default stack sizes after server morning reboot so I checked the files and did a o.reload StackSizeController

Heres what console hit back with:

StackSizeController was compiled successfully in 1078ms

(12:01:03) | [Stack Size Controller] Reverting stack sizes to vanilla defaults.

(12:01:03) | Failed to call hook 'Unload' on plugin 'StackSizeController v4.1.3' (NullReferenceException: Object reference not set to an instance of an object)

at Oxide.Plugins.StackSizeController.GetVanillaStackSize (ItemDefinition itemDefinition) [0x00000] in <7e7ff853f2d84f398b3ec1cf2b64b8ff>:0

at Oxide.Plugins.StackSizeController.RevertStackSizes () [0x00052] in <7e7ff853f2d84f398b3ec1cf2b64b8ff>:0

at Oxide.Plugins.StackSizeController.Unload () [0x0000d] in <7e7ff853f2d84f398b3ec1cf2b64b8ff>:0

at Oxide.Plugins.StackSizeController.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x000c8] in <7e7ff853f2d84f398b3ec1cf2b64b8ff>:0

at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <206a0f2c6ee141f38e2ad549cde44d70>:0

at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <beb2b64691c64e2b95b99491bd85442c>:0

at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <beb2b64691c64e2b95b99491bd85442c>:0

(12:01:03) | Unloaded plugin Stack Size Controller v4.1.3 by AnExiledDev/patched by chrome

(12:01:04) | [Stack Size Controller] Acquiring vanilla defaults file from official GitHub repo and overwriting; https://raw.githubusercontent.com/AnExiledDev/StackSizeController/master/vanilla-defaults.json