Custom subpanel on create view is missing with upgrade to v12.0.0

I have this situation with the Opportunities module. We have a 2 subpanel custom on the create view of opportunity. This works fine on the 11.3.0 version.

We have a clone instance with version 12.0.0 where these subpanels are no longer visible in the creation view. They are only visible in the Edit view of the opportunity.

creation view:

Edit View:

Has anyone gone through something similar? Any idea about what may be conditioning the custom?

Thanks All!!!