Heya!
Have you recently moved the initialization of NuclearCraft ores to postInit? I'm no longer able to set their Harvest Level with the mod Tool Progression, but I have previously been able to.

NuclearCraft-2.9d--1.12.2

Hola! No, I have not, so that is a bit bizarre...

Alright, thanks.

Okay, hopefully should be sorted for the next verison - I'll leave this open until it's definitely fixed.

I was told by the dev of Tool Progression that you are currently overriding the method public int getHarvestLevel(IBlockState state) without also overriding the corresponding setHarvestLevel appropriately, doing so should fix it.

Did this issue get fixed?

No I'm afraid not :/

Hmmm... don't know what the issue is then - I'm setting the harvest levels and getting the same harvest levels, so I don't actually know what I'm doing wrong...

To scoot around this issue, would a config option for the harvest levels of the ores do the trick?

Sorted :)

That works for me :)