Diagnosis
In the dunning proposal for insurance, you cannot dun &V1& items.
The items were posted in company codes configured for dunning bycollection strategy due to the grouping setting (Group by field).
Collection strategies are not supported in dunning by dunning procedurefor insurance companies.

Procedure
Restrict the selection of the mass activity to the company codes forwhich no grouping is defined.
You can dun documents that should be dunned by collection strategy usingthe dunning run of Contract Accounts Receivable and Payable(transactions FPVA and FPVB).