Formula-URL redirect triggers unsaved changes dialog even with “Auto save when redirected away from the page” enabled

I'm experiencing an unexpected behavior when saving a child record and redirecting to its parent record using a Formula-URL field.

Application structure

• Parent table: Product request
• Parent DBID: bvcry7xy6
• Child table: Products
• Child DBID: bvcry7xy7
• Relationship field in the child: Related Request, FID 108
• Parent Record ID lookup in the child: [RECORD ID# REQUEST (HEADER)], FID 186
• Formula-URL field used as Save: FID 222

The child record is initially opened using: URLRoot() & "db/" & "bvcry7xy6" & "?a=er" & "&rid=" & ToText([RECORD ID# REQUEST (HEADER)]) & "&ifv=1&hs=1" 

This structure work well untill 10/05 but now 11/05 I see this dialog message.