Still found the error in my logs:
Failed to call hook 'OnCardSwipe' on plugin 'PuzzlePoints v1.4.0' (InvalidOperationException: Collection was modified; enumeration operation may not execute.)
at System.Collections.Generic.List`1+Enumerator[T].MoveNextRare () [0x00013] in <47fc8c70fa834cbf8141d7c1a7589125>:0
at System.Collections.Generic.List`1+Enumerator[T].MoveNext () [0x0004a] in <47fc8c70fa834cbf8141d7c1a7589125>:0
at Oxide.Plugins.PuzzlePoints.OnCardSwipe (CardReader cardReader, Keycard card, BasePlayer player) [0x00066] in <ce792f647be648c380f31b4b697800f7>:0
at Oxide.Plugins.PuzzlePoints.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x001a1] in <ce792f647be648c380f31b4b697800f7>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <cd9a02fd331347bd82d550bb1a9c8e9f>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <b76ec77c47d1449e92b2baab8603843d>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <b76ec77c47d1449e92b2baab8603843d>:0