Elasticsearch index not getting created when add_field is used

Elastic Stack Logstash
2

looks to me the error is around the else if conditions and the way to set the add field, instead you should use nested else conditions, try this below,

if "data_one" in [data] {
    		mutate {
				add_field => { "Desc" => ["Snap" ] }
    		}
    	}  # end if "data_one"
    	else {
			if "data_two" in [data]  {
				mutate {
					add_field => { "Desc" => ["Snaptwo" ] }
				}
			} # end if "data_two"
			else {
				if "data_three" in [data]  {
					mutate {
						add_field => { "Description" => ["Snapthree" ] }
					}
				} # end if "data_three"		
			} # end 2nd else
		} # end 1st else

also, another similar post