Be sure to update Minecraft to 17W49A if you have recently installed Snapshot 17W48A which, among other things, contained quite a few bugs. At least, this snapshot will save you from the majority of visible errors found in the last week.
Full Snapshot 17W48A changelog – Minecraft.net
As expected, Snapshot 17W49A has prepared for players a few new features: added tags used to identify the blocks, which allows you to simplify and speed up the work with the date packs. If you want then you can create your own tags containing specific blocks and items.