The blocks that came in the snapshots for the 1.20 update are not present. That is, they are not available through commands, crafting or the creative menu. The new order in the creative menu dedoch however already.
I have not set anything special and the bug occurs with the option Latest developer version or a manual installation both in all gamemodes. 
In the picture is an example with the bamboo blocks.

The error occurs in snapshot 22w46a, but I was not able to find it in the affected versions tab.