I believe that should have been fixed in 1.8.4 actually.
When you delete the schedule, if you go to the Displays page, what is the icon in the Status column for your display?
My guess is you don’t have XMR configured correctly and so the CMS is removing the schedule, but the Player isn’t being notified that it should collect. It will pickup that change next time it collects from the CMS on its background collection schedule as a fail-safe in any case.