Excuse my English I'm French.
I play in version 1.20.1.
I have the simlpyskills mod and all its dependencies updated :

• puffish_skills-0.11.3-1.20.2-fabric.jar
• spell_engine-0.12.5+1.20.1.jar
• spell_power-fabric-0.9.19+1.20.1.jar
• cloth-config-11.1.118-fabric.jar

I deleted levelZ et jobsaddon (i I first thought that the problem came from these mods).
But the melee damage and spell damage just do not apply. The health leveling is working, the health increase when i level up it.
But the damage does not increase.

Here is a demonstrative video : https://youtu.be/jjorr0sOOoM

Ok, I played with no other mod and it works. So I'm going to see which mod it doesn't work with.
However, I noticed that melee damage increased magic damage.

As you've discovered, you have another mod interfering with the attributes.

In regards to melee damage increasing magic. This isn't a thing to my knowledge. Can you provide a demonstration?

I found the 'incompatible' mods: create and the majrusz mods