Confirmation email not sent when allowed from #admin_approve_link

Hello,

Needing your help again, It seems that when the administrator approve an appointement via the #admin_approve_link the confirmation email is not sent, which is weird cause the status is changed to approved.

And the confirmation email is sent when approved manually in the back-office.

What I did wrong?

PS: On the cancellation every things works, and in the free version also (preprod env).

Thank you in advance.