Summary
The Concrete double-slabs are not able to be placed like other double-slabs are when using the “setblock” command.
Other double_slab vanilla blocks currently existing in the game are able to be set when using the command, so it seems that there might be some functionality hook in missing from the Concrete double-slabs. This applies to all the colours:
white_concrete_double_slaborange_concrete_double_slabmagenta_concrete_double_slablight_blue_concrete_double_slabyellow_concrete_double_slablime_concrete_double_slabpink_concrete_double_slabgray_concrete_double_slablight_gray_concrete_double_slabcyan_concrete_double_slabblue_concrete_double_slabpurple_concrete_double_slabgreen_concrete_double_slabblack_concrete_double_slabred_concrete_double_slabbrown_concrete_double_slab
Repro Steps:
In the text field, type the setblock command for any of the concrete double slabs, like so:
/setblock ~ ~ ~ black_concrete_double_slabObserve it fails with a syntax error sent to the chat
Video: