This happens for me with the latest 5.169.0 builds.
The result is that every action of anyone with sniper permissions results in a "No Brush selected" message, chests can't be opened, blocks can't be broken, trying to select a brush or change the tool don't work.

[13:18:21] [Server thread/ERROR]: Could not pass event PlayerJoinEvent to VoxelSniper v5.169.0-SNAPSHOT-jnks299-git065ccc1 org.bukkit.event.EventException at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:294) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:36) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:501) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:486) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at net.minecraft.server.v1_7_R1.PlayerList.c(PlayerList.java:225) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at net.minecraft.server.v1_7_R1.PlayerList.a(PlayerList.java:116) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at net.minecraft.server.v1_7_R1.LoginListener.c(LoginListener.java:78) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at net.minecraft.server.v1_7_R1.LoginListener.a(LoginListener.java:42) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at net.minecraft.server.v1_7_R1.NetworkManager.a(NetworkManager.java:149) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at net.minecraft.server.v1_7_R1.ServerConnection.c(SourceFile:134) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at net.minecraft.server.v1_7_R1.MinecraftServer.u(MinecraftServer.java:655) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at net.minecraft.server.v1_7_R1.DedicatedServer.u(DedicatedServer.java:250) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at net.minecraft.server.v1_7_R1.MinecraftServer.t(MinecraftServer.java:545) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java:457) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:617) [craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] Caused by: java.lang.NullPointerException at com.thevoxelbox.voxelsniper.Sniper.displayInfo(Sniper.java:431) ~[?:?] at com.thevoxelbox.voxelsniper.VoxelSniperListener.onPlayerJoin(VoxelSniperListener.java:983) ~[?:?] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0_51] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[?:1.7.0_51] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.7.0_51] at java.lang.reflect.Method.invoke(Method.java:606) ~[?:1.7.0_51] at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:292) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.3-2-g85f5776-b3023jnks] ... 15 more

We changed some things around, so you have to set up your permissions correctly. I'll patch this NPE in just a minute.
Here is what changed for the 5.169.0 builds:
http://voxelwiki.com/minecraft/VoxelSniper#Update_to_5.169.0