I play in a server with some mods installed, such as the jei mod or optifine. 

The problem is that when i kill cows or any other animal sometimes they don't drop anything, and thats really an issue because i need food. I think it may be a problem because of the mods, and i will like you to tell me if that's the problem, and if so, to tell me how to fix it, or if the problem is something else. 

Here are all the mods installed: 

• Voxelmap
• Vanilladeath chest

• useful backpacks
• u team core
• twiligthforest
• optifine
• jei
• ctm
• chisel
• biomes o plenty
• security craft

They all are installed for the 1.12.2 version

Thank you