When a CT has a reference property to another property, and it is marked as "multiple", then the generated app does not correctly configure the identifierToPathConverter node. Thiis causes links to be stored as paths instead of UUID's, which will cause problems in templating and other places.
(identifierToPathConverter has no "class" property)

When the CT property is not multiple, then the identifierToPathConverter is created correctly in the app.
(identifierToPathConverter has the correct "class" property: "info.magnolia.ui.form.field.converter.BaseIdentifierToPathConverter")

—

Given we have a CT with a CT-based app,
when the CT defines a filed with a reference to another type, and if the field allows multiple values:

# ...
model:
  nodeType: mt:tourOffice
  properties:
    - name: tourGuides
      type: reference:tourGuide
      multiple: true
# ...	  

Then the definition app claims a MINOR PROBLEM

Definition: tourOffices-app
Origin: /content-type-examples/apps/tourOffices-app.yaml
Details: Property [identifierToPathConverter] is set to null in definition.
Location: tourOffices-app/subApps/detail/editor/form/tabs/default/{name=name, i18n=false, required=true, type=String, fieldType=text}/tourGuides/tourGuides/identifierToPathConverter
Type: Source data processing problem
Severity: MINOR

When removing the multiple: true, there is no more problem.

This is a regression.

The given example has worked. (GIT: content-type-examples).
The above linked repos also contains bootstrpable data, which was produced months ago. In this (old) data, the multi-value content is stored like this:
[551d6005-20ec-4216-907b-87a0fd3f99b6, 58ba8e48-f404-4593-90b0-19116bcfed10].
When I create a new Tour office right now, the data now is stored with the node-path and not with the node-UUID (anymore).