I am using this command:
/execute @p[score_Target_min=1] ~ ~ ~ spreadplayers ~ ~ 6 30 false @e[type=Silverfish]

The command works, to an extent. It does teleport all Silverfish in the world to me, when my Target score is 1 or more, and it does spread the Silverfish in the manner specified in the command, BUT the Silverfish do not teleport to me when I move around 100 blocks or more away from the command block.

I have tried messing about with Range specifiers, but cannot get the command to work when I am too far from the command block.

I'd like to know why the command stops working when I am too far from it. If it's possible to extend the command's range, please let me know! If that's not possible to do, perhaps this is a bug, or is a feature which should be added.

Please note #1- The usual spreadplayers command works as intended, when it targets players and does not have this strange range limitation specific to mob entities.

Please note #2- The chunk in which this command block is loaded, does not unload when I move around 100 blocks from it. My computer handles Minecraft very well and is set to renders 16 chunks. To make sure, the command block is positioned in the spawn chunk, so it will never unload.