ASM TMOS v13 Unnable to change enforcement mode after create a default policy.

After create a simple policy (default parameters and with no virtual server) using TMOS v13 HF2 I found that I am unnable to change enforcement mode for example to change to transparent. After I change the enforcement readiness period for example from 7 to 5 I found that I am allowed to change the enforcement mode.

Did someone notice that or know why is this behavior?

Regards Ronald