Bixby will not disable routines. So "disable the Reddit routine" does not work, it provides confirmation that it has disabled the routine, in a string of commands, but doesn't in reality. It also will not recognize the "disable the Reddit routine" command as a single command if the routine is built. "Enable the Reddit routine" works.
Both enable and disable routine commands should work, please fix.
If you don't want to use the routine, change it to start manually -- or delete it and recreate it when you want to use it again. This is a workaround until it gets fixed. Put in on an error report and clear your device cache. The proper way to report this is to put in an error report with Samsung. Users cannot fix the issue. Although, I am quite sure it will resolve on deleting the cache.
