How do you configure IPv6 these days in Check Point?
If you have Static NAT on an IPv4 address in the object you must also use it on the IPv6 address or you get an error.
You can do a sort of a workaround by adding the same address on the object also for the NAT address. But then you run into problems where you were not expecting them. The Static NAT will push something on the network and your host may shutdown it's IPv6 address as it will detect a Duplicate IP.
I have raised the issue with TAC and I am waiting for their response.
The workaround is to create 2 objects. An IPv4 object WITH static NAT and an IPv6 object WITHOUT NAT.
But if you have dozens of rules with this object you have a lot of work.