Problem FSM

There is a problem that when I tried to design a FSM, the code never enters to that part. I simulated the same code in ModelSim and it was working fine.

FSM_I2C : process(current_state,next_state,i2c_start,Flag,i2c_clk_previous_internal, id2c_scl_i_clock,i2c_sda_oe)
	begin
		--if (RISING_EDGE(Clk)) then	
			case current_state is
				when IDLE =>
					counter_variable <= 7;
					if i2c_start = '1' then
						next_state <= START;
						i2c_sda_oe <= '1';
					else
						next_state <= IDLE;
					end if;
				
				when START =>
					if Flag = '1' then
						i2c_sda_wr <= '0';
						next_state <= ADDRESS;
					end if;
		
				when ADDRESS =>
					if counter_variable /= 0 then
						if id2c_scl_i_clock = '1' and i2c_clk_previous_internal = '0' then
							counter_variable <= counter_variable - 1;
							i2c_sda_wr  <= I2C_ADDRESS_SENSOR(counter_variable-1);
						end if;
					else
						if id2c_scl_i_clock = '1' and i2c_clk_previous_internal = '0' then
							i2c_sda_wr  <= I2C_WRITE_RW;
							counter_variable <= 7;
							next_state <= ACK;
						end if;
					end if;
				
				when ACK =>
					i2c_sda_oe <= '0';
					if i2c_clk_previous_internal = '0' and id2c_scl_i_clock = '1' then
						next_state <= IDLE;
					end if;
				
				when others =>
					next_state <= IDLE;
			end case;
		--end if;
	end process FSM_I2C;

this is just a part of the I2C algorithm. In this case, I'm just implementing sending the address to see if my code is working fine. However, this is the output

Only works when I put inside the FSM a conditional IF(RISING_EDGE(CLK)), but I don't understand why since I'm updating all the variables in other process.

	process (Clk,reset_reset_n)
	begin
		if reset_reset_n = '0' then
			current_state 		 		<= IDLE;
			id2c_serial_scl	  		<= '0';
			id2c_serial_sda	   	<= '0';
		elsif (RISING_EDGE(Clk)) then
			current_state 		 		<= next_state;
			id2c_serial_scl			<= i2c_clk_previous_internal;
			id2c_serial_sda		 	<= id2c_serial_sda_o_internal;
			id2c_scl_i_clock 			<= i2c_clk_previous_internal;
		end if;
	end process;