Related entity being unlinked instead of soft-deleted

I have entity hierarchy like
1 Student {onDelete Cascade} -> M Enrollments
1 Enrollment {onDelete Cascade} -> M Enrollment Subjects
1 Subject -> M Enrollment Subjects

Enrollment Subjects is a linked entity. All entities are soft deletable and each FK is mandatory. I am using TokenList for Enrollments Subjects in Enrollments screen, on removing items from TokenList, Enrollments Subjects entities are being unlinked instead of soft deleted and this results in non-null constraint violation (enrollment in enrollments subjects is not null).

I have gone through DeletePolicy but if not specified, entity should be deleted. Related entities are successfully being deleted everywhere else but they are in 2 entity hierarchy only. What am I missing?

Usually TokenList component is used for adding or removing many-to-many associations between associated entities. So this is its default behavior.
CUBA team will be able to suggest something if you show some code samples (entity definition, editing screen).