Modern APM Message Box

Hi etherchannel01 

You can still modify the message box and all elements in the modern policy, the difference from the old one to the new one is that in the new one you can´t see the current code, but you can still editing the content inserting the code. with the old one you can see the original code and work over it.

Please follow this link:

https://community.f5.com/t5/technical-articles/apm-advanced-customization-examples-with-modern-template-v15-1/ta-p/288979

Hope it´s work.