Hi, I still do not understand why you use update group 000015 - when you have 000012 and the transaction is not relevant for 000012, the system switches to the next possible update group, for example 000018. You can set the update group in v_t014.
It is hard to say why the setup for your new credit control area did not work without going through all the assignments that you performed and check the master data. Program check_cm is a very easy way to see what exactly is going on, because it shows you the relevant assignments and S066/S067 values.
Please post the result of check_cm for your document for credit control area with 000012 update group- all the info that you get there for your order.
Update group 000015 works with open delivery value and open billing values, but you set a check for open order value. This will not work, because unless the credit limit is previously exceeded, the order will not be blocked.
Max open item % is used when you check for open items, which are overdue (you have not activated it in OVA8). Percentage of overdue open items older than number of days specified in nodays openI field - should not go higher than this value, otherwise the order is blocked.