*facepalm*

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/chunks/ChunkSection1_13.java

@@ -118,7 +118,7 @@ public class ChunkSection1_13 implements ChunkSection {
         boolean directPalette = false;
 
         if (bitsPerBlock == 0) {
-            bitsPerBlock = 13;
+            bitsPerBlock = 14;
         }
         if (bitsPerBlock < 4) {
             bitsPerBlock = 4;