Hi Nicolas. > It doesn't look like a bug. The OP may have missed > `org-agenda-time-grid' variable.
¿What is OP?. If I do the same on emacs 25.1 I get the expected behaviour. So something has changed between 25.1 and 26.1. ¿What is the change needed? for having the same result on both emacs versions 25.1 and 26.1. Regards