Block names are case-sensitive

When you use /setblock, it will not accept spellings of tile names that are capitalized. For example,

/setblock ~ ~ ~ Lava

does not work while

/setblock ~ ~ ~ lava

does.
Aditionaly,

/setblock ~ ~ ~ Minecraft:lava

does not work, despite "Minecraft" being a proper noun and thus usualy being capitalized.
Finaly, tab-complete is case insensitive, making this seem even more like a bug.