stored procedure behaving unexpectedly

DELIMITER $$
CREATE OR REPLACE DEFINER=`dbadmin`@`%` PROCEDURE `FAR_STAGE_BP_IMPACT`()
BEGIN
		UPDATE FAR_BREAKS_STAGE cod
		INNER JOIN FAR_IBOR_BP_IMPACT_DATA tna ON (cod.FUND_SYMBOL = tna.ACCT_CD_FMRID)
		SET 
		cod.IBOR_TOTAL_NET_ASSETS_USD = tna.MKT_VAL_USD,
			cod.BREAK_BP_IMPACT =
			CASE
				WHEN 
				IFNULL(cod.IBOR_TOTAL_NET_ASSETS_USD,0) = 0 THEN
					0
					WHEN cod.DEBIT_CREDIT = 'Debit' THEN
					CAST(IFNULL(((cod.USD_EQ_Amount / cod.IBOR_TOTAL_NET_ASSETS_USD) * -10000), 0) AS DOUBLE(10, 4))
				ELSE
					CAST(IFNULL(((cod.USD_EQ_Amount / cod.IBOR_TOTAL_NET_ASSETS_USD) * 10000), 0) AS DOUBLE(10, 4))
				
			END
		WHERE
			tna.ACCT_CD_FMRID IS NOT NULL and cod.REC_TYPE = 'IBOR';
			
					
			UPDATE FAR_BREAKS_STAGE cod
		INNER JOIN FAR_ABOR_BP_IMPACT_DATA tna ON (cod.FUND_NUMBER = tna.ACCOUNT_NUMBER_IO)
		SET 
		cod.ABOR_TOTAL_NET_ASSETS_USD = tna.TOTAL_NET_ASSETS_USD,
		cod.BREAK_BP_IMPACT =
			CASE
				WHEN 
				IFNULL(cod.ABOR_TOTAL_NET_ASSETS_USD,0) = 0 THEN
					0
				WHEN cod.DEBIT_CREDIT = 'Debit' THEN
					CAST(IFNULL(((cod.USD_EQ_Amount / cod.ABOR_TOTAL_NET_ASSETS_USD) * -10000), 0) AS DOUBLE(10, 4))
				ELSE
				 CAST(IFNULL(((cod.USD_EQ_Amount / cod.ABOR_TOTAL_NET_ASSETS_USD) * 10000), 0) AS DOUBLE(10, 4))
			END
			
		WHERE
			tna.ACCOUNT_NUMBER_IO IS NOT NULL and cod.REC_TYPE = 'ABOR';
			
          UPDATE FAR_BREAKS_STAGE bs SET 
			bs.FUND_BP_IMPACT =
			CASE WHEN 
			 bs.REC_TYPE= 'IBOR' THEN
			 fn_get_sum(bs.FUND_SYMBOL, 'IBOR')
			ELSE
		  fn_get_sum(bs.FUND_SYMBOL, 'ABOR') 
          END;
			
                
END$$
DELIMITER ;

 This stored procedure which is updating same table thrice with joins with other table is not running properly. sometimes it is only updating ABOR data and sometimes it is updating only IBOR data. sometimes it update FUND_IMPACT column, other times don't execute it at all. Please suggest why it is behaving like that. Timeout is set as 600 ms.