Method not invoked by instance for unknown reason

i have a class with 3 methods and 3 instances.
each instance invokes the method with the same name the instance has.
instance X invokes method X

on the schema and so on instances, only 3 fields: username (attribute string), password (attribute encrypted string), and “execute” , the method .

In the automation/simulation, the 2 first instances invokes correctly their method:

[----] I, [2017-08-08T16:30:53.316620 #884:909bc4] INFO – : Following Relationship [miqaedb:/MyNameSpace/Methods/InstanceX#create]
[----] I, [2017-08-08T16:30:53.332286 #884:909bc4] INFO – : Updated namespace [miqaedb:/MyNameSpace/Methods/InstanceX#create MyDomain/MyNameSpace]
[----] I, [2017-08-08T16:30:53.362278 #884:909bc4] INFO – : Updated namespace [MyNameSpace/Methods/InstanceX SFR/MyNameSpace]
[----] I, [2017-08-08T16:30:53.373150 #884:909bc4] INFO – : Invoking [inline] method [/MyDomain/MyNameSpace/Methods/InstanceX] with inputs [{}]
[----] I, [2017-08-08T16:30:53.374740 #884:909bc4] INFO – : <AEMethod [/MyDomain/MyNameSpace/Methods/InstanceX]> Starting

on the third, the method is not invoked as if the field for method in instance was not filled.

there are of course no error messages in logs
and the simulation UI says all is ok.

any ideas?

the reason why the third instance do not invoke the method is because one field before method field is a password field, which was empty.

production.log tells about decrypt error. But automation.log, evm.log says nothing. And the simulator says all was correct…