There exists items that cannot be limited, for example:

both the Chinese New Year Knocker, and the Skull Door Knocker. Along with the wreaths, both Easter and Christmas. As well as the Christmas Lights, that one I did not discover myself however, so not sure which christmas lights. You are more than welcome to try yourself too.

assets/prefabs/misc/xmas/wreath/christmas_door_wreath_deployed.prefab

assets/prefabs/misc/easter/door_wreath/easter_door_wreath_deployed.prefab

assets/prefabs/misc/halloween/skull_door_knocker/skull_door_knocker.deployed.prefab

assets/prefabs/misc/chinesenewyear/dragondoorknocker/dragondoorknocker.deployed.prefab

There was, however, a thread someone created mentioning Delux Christmas Lights, so if I had to guess someone else noticed the Christmas Light issue, and likely those are the Christmas Lights I mentioned.

I believe that something should be mentioned somewhere in the documentation/description of the plugin on uMod, but am not sure if you were aware of this. Or, somehow fix this issue. Someone I know has an older implementation from verion 1.0.3, and it used entities, this allowed it to actually see or at least tell that the entity is existing and has been placed, however, still fails to enforce the limiting upon said entity. In this current implementation, the plugin doesn't even recognize the items existance.