Recurrence rule in “Custom …” modal always defaults to the first option when editing monthly recurring dates

Problem/Motivation

When editing a node with a Recurring dates field set to repeat monthly (e.g., “first Tuesday of the month” across specific months), choosing "Custom …" opens a modal where the displayed recurrence rule is the first preset option (e.g., “Monthly on day 4”) rather than the correctly stored rule (e.g., “monthly on the first Tuesday ...”).

Steps to reproduce

1. Edit a node with a Recurring dates field configured to repeat monthly.
   Example configuration:
   • Start date: Tuesday, March 4, 2025 – 10:00 am
   • Recurrence: Monthly on the first Tuesday of March, April, May, June, July, and August
   • End date: Wednesday, March 19, 2025 – 11:59 pm

2. In the Recurring dates field, choose "Custom …"
   
3. Observe the recurrence rule shown in the modal dialog
   

Actual result

The recurrence rule always shows the first option in the list.
Example: "Monthly on day 4" is displayed instead of the actual stored rule ("Monthly on the first Tuesday").

Expected result

The recurrence rule in the modal should match the saved recurrence pattern for the field.

Additional notes

This issue occurs only when editing a node with a pre-existing monthly recurrence rule. It does not occur when editing a node with a pre-existing daily, weekly, or yearly recurrence rule.