Over here: Region3 | Documentation - Roblox Creator Hub
you can see that the new constructor of Region3 does not change the position, only the min and max size. You should change the CFrame property of region to the player with an offset.
Oh, sorry. I noticed that in the code example roblox has given it is explained that the first parameter of new is the position. Have you tried make the offset bigger than 5 on all the axis?
just position 2 parts such that they form a rectangular prism, copy their vector3s then rearrange their components so all the negative values are in the first minimum vector3