Why are we seeing devices being discovered and immediately placed into maintenance
You may see device being discovered into the Spectrum topology without your input if you have set from the VNM model > Information tab > Trap based continuous discovery sub view :
Unmanaged trap handling set to “enabled”
New devices in Maintenance to “yes”
This means that when traps are received from devices not already discovered in Spectrum they will be discovered / modeled and then immediately placed into maintenance mode.