FQDN node regression 11.6.0-HF5 ?

I'm using FQDN nodes in my AWS F5 VEs

After upgrading to 11.6.0-HF5 the FQDN resolution/instantiation doesn't work any more.

The ephemeral nodes are not created, and the availability of the node remains "

Unknown (Enabled) - Querying DNS resolver is enabled, but result is not available yet

Of course the DNS resolution is working (I can 'dig' any hostname from ssh)

Here is my test case:

tmsh create ltm node my_test_google_fqdn fqdn { autopopulate enabled down-interval 2 interval 15 name google.com }

In 11.6.0-HF4 it works as expected, and generates this nodes:

In 11.6.0-HF5 it generates this list:

Do you know something that changed in HF5 ?

Maybe in HF5 there is some configuration missing that was previously optional.

Thanks for any pointers.

Angelo.