Complex blocks cause NBT overload and crash anyone entering the area.

Interactions 1.9.1
_spongeforge-1.12.2-2838-7.1.8-RC3970
LittleTiles_v1.5.0-pre135_mc1.12.2

Server error:
[21:11:36] [Netty Epoll Server IO #15/ERROR]: [FML]: NetworkDispatcher exception
io.netty.handler.codec.EncoderException: java.lang.IllegalArgumentException: unable to fit 8345973 into 3
at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:125) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:816) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:723) ~[minecraft_server.1.12.2.jar:?]
at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:113) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:816) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:723) ~[minecraft_server.1.12.2.jar:?]
at io.netty.handler.codec.MessageToMessageEncoder.write(MessageToMessageEncoder.java:101) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:816) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:723) ~[minecraft_server.1.12.2.jar:?]
at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher.write(NetworkDispatcher.java:548) ~[NetworkDispatcher.class:?]
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:801) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:814) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:794) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:831) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.DefaultChannelPipeline.writeAndFlush(DefaultChannelPipeline.java:1032) ~[minecraft_server.1.12.2.jar:?]
at io.netty.channel.AbstractChannel.writeAndFlush(AbstractChannel.java:296) ~[minecraft_server.1.12.2.jar:?]
at net.minecraft.network.NetworkManager$4.run(NetworkManager.java:245) [gw$4.class:?]
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163) [minecraft_server.1.12.2.jar:?]
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:403) [minecraft_server.1.12.2.jar:?]
at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:304) [minecraft_server.1.12.2.jar:?]
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858) [minecraft_server.1.12.2.jar:?]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_212]

You're using a really outdated version of the mod. Update both LittleTiles and CreativeCore to their newer version and check if the issue persists.

I will close this issue for now as it should be fixed by now. If the newest version still doesn't work reopen this issue.