After many iteration I'v figure out that rtm.tasks.getList return "Status: 105, reason: Service currently unavailable." because of some bugs that don't return repeatable tasks or any list that contains it.
I try filter:
"status:incomplete AND dueBefore:10/06/18 AND dueAfter:05/06/18" - for API: Status 105; web-app: return 3 task (1 is repeatable)
"name:word AND status:incomplete AND dueBefore:10/06/18 AND dueAfter:05/06/18 " - for API: Status 105; web-app: return 1 repeatable task contained "word" in name
"not name:word AND status:incomplete AND dueBefore:10/06/18 AND dueAfter:05/06/18 " - for API: return 2 task; web-app: return 2 task (0 is repeatable)
"status:incomplete AND dueBefore:10/06/18 AND dueAfter:05/06/18 AND isRepeating:true" - for API: Status 105; web-app: return 1 repeatable task
"status:incomplete AND dueBefore:10/06/18 AND dueAfter:05/06/18 AND isRepeating:false " - for API: return 2 task; web-app: return 2 task (0 is repeatable)
may be problem is in "repeatable" property or count of completed instance of this kind of tasks. I don't know. but it's fact that any request don't return this kind of tasks
I use RTM API Community Edition