Ore blocks are only being destroyed not dropping ore. I know you need an iron pick axe to mine them.
It was working fine yesterday. Today I updated the Resource Pack, Shader Pack, OptiFine and Minecraft Forge.
Now I have this problem. Does anyone have a fix or heard of this?
Latest version - 1.12.2Forge - 1.12.2-126.96.36.19905
Yeah, block lag is my first thought also. Check F3 and make sure you have enough memory allocated *first*, otherwise Minecraft will be spending it's time churning memory instead of processing for block drops.
I would also suggest playing pure Vanilla to see if you still have the problem, and *THEN* add JUST Optifine (no shader pack), see if things behave normally. THEN add JUST Optfine PLUS the shader pack (I'm guessing the shaders are being used through Optifine). Still behaving? Good! Watch the memory in the upper-right corner while you are doing this testing also. Make sure you have enough.
Now try JUST Forge without mods, NO Optifine. Still good? JUST Forge WITH mods, best if you add them one-at-a-time. How are the block drops?
Try Optfine (No Shaders) WITH Forge (No Mods). Add the mods back in, then the Shaders.
Eventually you'll get to a point where things stop working, or you'll see what you may have missed and get the whole smash working. The high-end 256x resource packs can be greedy pigs. Shader packs, same. If your machine is busy churning memory, it won't have time to drop blocks for you. If Memory isn't the problem, rebuilding the setup you describe and TESTING each piece at a time can really help sort out where things break, and how to unbreak them.