Potential Issues

CmdUseItem rejected 

In uSurvival there is a predictive cooldown that occurs that seems to be blocking clients usage of items if it happens out of sequence from what is expected. I believe this to be a bug in this function as it stands as this occurs in the default uSurvival installed from the asset store. If your clients are having an issue hitting trees or harvesting properly, look in the servers logs for a Command Rejected notice. If you see this, then you are experiencing this issue.