Here are screenshots that explain what I mean
This doesn't just affect iron blocks, it's the same for me with wooden planks, cobblestone and some others that I happened to have in my chests, so it's probably the same for all blocks.

Using the woodcutter it works properly, even though some items don't really fit into it material wise, like iron blocks.

It will be complicated to test them one by one...
I will try to find the causation of the problem.

Hello,

I have look on my side and I don't have the problem.
Do you have any other mods that might conflict?

Not sure what mod could cause it... here's the mod list (ignore the disabled 1.17 versions)

Try the latest version to see if the problem persists, there have been some changes.