Intermittent behavior of Start Process smart service in MNI

Question

Hello All, 
 We have a requirement to run the multiple process models as per schedule. The Scheduler will be responsible to identify which process to be triggered and when. 
 For example we are maintaining below data in records- Processname - time - UUID

Process Name 
 Time 
 UUID

process 1 
 2:30:00PM, 5:30:00 PM 
 uuid1

process 2 
 2:30:00PM, 5:35:00 PM 
 uuid2

process 3 
 8:05:00 AM,2:30:00PM, 5:35:00 PM 
 uuid3

process 4 
 10:05:00 AM,2:30:00PM 
 uuid4

process 5 
 10:05:00 AM,2:35:00PM 
 uuid5

process 6 
 12:05:00 PM,2:45:00PM 
 uuid6

Now parent process is running and checking in each 5 mins and checking which process to be executed. Then it fetch the UUID of those processes and get the Process Model ID. This process model id will be used to call "Start Process" smart service with (MNI), each for identified process. 
 I am using Start Process smart service because I am maintaining UUID in DB and need to get the processes dynamically. 
 So here as per above example, at 2:30:PM I have 4 process models (process 1, process 2, process 3, process 4) to be triggered. Now currently my parent process model is identifying 4 processes to be triggered and triggering them. 
 The issue which I am facing is intermittent. All 4 nodes gets executed at times. And some times only one process model gets executed and others remain untriggered. When I check the "Start Process" node properties in monitoring, then it shows the spawned nodes as below.

Node 
 Status

start process

start process 
 Completed

I am not sure what can be the issue behind this intermittent behavior. Can anyone help here?