The mangrove planks, which is another type of wooden planks, cannot be used to repair wooden tools/weapons and shields. This is inconsistent with other types of wooden planks and not in parity with Java.
How to Reproduce
- Get wooden tools/weapons, or shields with less durability, and mangrove planks
- Place an anvil
- Try to repair it with mangrove planks
You cannot repair them.
You should be able to.