Yes, I get your point. Many of us do have savings account in various banks, so we can switch from one bank to another, in the event of FPX system down in one of the banks.
Scenario A
Attempt 1: Try to top-up RM 100. Select Bank A. Failed, due to no unit.
Attempt 2: Try to top-up RM 100. Select Bank A. Failed, due to no unit.
.
.
.
Attempt 9: Try to top-up RM 100. Select Bank A. Succeed to capture 100 units, but FPX system in Bank A is down, and the units are lost.
Attempt 10: Try to top-up RM 100. Select Bank B. Succeed to capture 100 units, and pay RM 100 via FPX from Bank B.
I understand that this Scenario A is quite common when FPX may not work for some banks, but we do not usually choose Scenario B.
____________
Scenario B (assuming that FPX system in all banks is ok.)
Attempt 1: Try to top-up RM 100. Select Bank A. Failed, due to no unit.
Attempt 2: Try to top-up RM 100. Select Bank B. Failed, due to no unit.
Attempt 3: Try to top-up RM 100. Select Bank C. Failed, due to no unit.
.
.
.
Attempt 9: Try to top-up RM 100. Select Bank I. Failed, due to no unit.
Attempt 10: Try to top-up RM 100. Select Bank J. Succeed to capture 100 units, and pay RM 100 via FPX from Bank J.
The "new design" of ASNB website seems to imply that we will change the bank for FPX payment, for each attempt of topping up ASNB fund.

Then if the internet banking for that bank was down, then you can't change bank at that point of time as well