Unfortunately I can't share the configuration of the client.
But we scheduled a maintenance window to configure the new Virtual Servers on the client environmet, like I've described above the tests from our laboratory, where we could reproduce the issue and perform the correction and I'll reply here if it solved or not the issue.
In the MW with the client, the issue was resolved only when we configured the sourde address as a single IP address /32 and the destination Any (0.0.0.0/0). As they already had others IP forwarding virtual servers working properly.
But, differing from our lab, the client use partitions, and the Rouite Domain ID of the partition is 10. The Common is 0.
The IP forwarding virtual servers are placed in the partition with the ID 10.
Whe in the partition with the route domaind ID 10, the BIG IP adds automtically the route domaind ID 10 into the IP address configured into the address lists created:
For example in one address list with two IPs, they were like this:
When we configure the IP forwarding virtual server using this list as source address, and configure the 0.0.0.0/0 in the destination, when we update the configuration of the VS the BIP IP adds automatically the route domain from partition Common and it changes to 0.0.0.0%0/0. We tried to add the route domain 10, configuring the destination as 0.0.0.0%10/0 so, the route domains will match between source address into the address list and the destionation mask (any), but the BIP IP system changes it again to 0.0.0.0%0/0.
So, we conclude that it could be a misbehaviour from BIG IP and openned a support case.