Modules in Lead Conversion that are supposed to be Optional are actually required to move to the next module

I have a number of custom modules that have been added to the Lead Conversion and are not Required:

When I go through the Lead conversion process in v14 or v25.1 Enterprise I cannot create a Contact Role unless I create an Opportunity, and I can't create a Partnership Opportunity unless I create all the other records above that even though they are not required.

The Create Opportunity is clickable but nothing else is.

If I fill the Opportunity then the create Contact Roles is clickable but all the others are disabled, and so on.

 

Has anyone else seen this?

I used to have a custom LeadConvert to populate some additional data for the custom modules, but this is now gone, so I don't believe that a customization is to blame.

Any tips on debugging would be welcome.

Thank you,

FrancescaS