I am not sure if my request would also qualify as a bug. I think form a UX perspective it is a bug. I am on Windows 10 (Joplin 1.0.216).
If you add an alarm to a note or a to-do, the ok-button is partially hidden by the interface, depending on the language (in my case german) it is even fully hidden. I added some pictures below. It is also not possible to confirm the alarm by hitting enter or any other key. This makes adding alarms to notes more cumbersome then it needs to be.
I see two easy solutions: 1. ‘Clear’ could be replaced with a trashcan icon 2. The description “set alarm” and the selection field could be moved to different lines. In that case the input would need more vertical space.
And I have another suggestion also related to alarms. Perhaps the time of the alarm could be part of the headline in the left pane. Perhaps in a smaller font below the actual headline or just in the same line. This would make it much easier to review several to-dos in Joplin and stay on top of things.