Nifi Registry migration with nested process groups

We have a scenario where PG-A has child PGs like PG-A1, PG-A2. Everything works fine with versioning of all PGs along with importing PG-A which imports all child PGs into any other Nifi Development instance. 

However, when we move the registry content from dev to UAT enviroment. Importing of parent PG give error like below. However, child PGs get imported individually without any issue. 

"The Flow Registry with ID f9eb8fe6-0176-1000-a53b-838685a98fb8 reports that no Flow exists with Bucket 29a08c71-a056-4e1a-8e8e-0f46abcc50c9, Flow fee2a7e1-3716-42ce-881f-071ef0240fd9, Version 10"

Can you please suggest anything to take of when doing this migration? Any workaround?

Thanks,

PR