In the 1.15 update they changed the name of the folder and basically all of the files within it... but left a "compatibility mode" where it'd still read the old ones correctly from the older /blocks/ folder. However using this mode means the new stuff won't work. So if you want everything to work, you need to update all of your file names to the new version using the /block/ folder. (Yes, they changed all of the block file names for no adequately explained reason.) Same for /items/ becoming /item/ now. The compatibility mode was a reprieve for those who are slow to update, but you can't lean on it forever if you want the new stuff to work.
You'll also find that the update broke a few things completely like chests, but that's a separate (and still very annoying) issue.
I hope that explains things.
Aaah, for the love of god.. They just have to make things more and more difficult, eh
Thanks for the explanation. I tried to look at the new and old files, and the names were the same, but it seems like i didnt check enough files.
Guess i have to update a lot of files then. Thanks a lot for the help, both of you!