After updating to latest 1.4.2 version, Hammer wouldn't work properly and stopped breaking ores. (I tested with obsidian and diamond hammers). They can however break vanilla ores.

Looking into it, I’m pretty sure I know what is causing it..

We also saw that the GUI to change aspect (identity mod) is broken. It worked in the 1.3.1 version

fixed in next update

I'm playing on the latest modpack version (1.5.1) and the hammer issue remains.