Behavior of Business Rule Calculation When Current Week Forecast is #MISSING

Summary:
Inquiry regarding whether the business rule for calculating weekly forecast differences (FcstWeekDiff) functions correctly when the current week's forecast value (Final->Forecast) is #MISSING.

Content (please ensure you mask any confidential information):
We are currently implementing a business rule to calculate the weekly forecast week-on-week difference (member name: FcstWeekDiff).
The current week's forecast uses the "Final" member in the Version dimension, while the previous week's forecast uses a substitution variable named FcstPreWeek1. This variable points to a member under the WeekVer hierarchy (e.g., Week17 週次W17 20250725) to represent the prior week's version.

The calculation is defined in the business rule as follows: