kind tricky to judge what you exactly did. but in principle you should be able to change between monitor and managed without loosing configuration. did you indeed just make that change or also changed from group to group or did something else?
also once you got to managed mode you can't manage them anymore on the IAP, you don't expect to be able to do both right?
[edit] or are you now trying to move all clusters to one new group with managed mode on? start with importing one cluster in a new group, have that pickup the config and then get the rest there.