Procd respawn parameters lost after /etc/init.d/program/restart

Hi,
When restarting a specific application with /etc/init.d/program/restart, respawn parameters are lost:
before :

ubus call service list '{"name":"program"}'

        "program": {
                "instances": {
                        "program": {
                                "running": true,
                                "pid": 4904,
                                "command": [
                                        "\/usr\/bin\/program",
                                ],
                                "term_timeout": 5,
                                "limits": {
                                        "core": "unlimited" 
                                },
                                "respawn": {
                                        "threshold": 3600,
                                        "timeout": 1,
                                        "retry": 0
                                },
                                "pidfile": "\/var\/run\/program.pid" 
                        }
                }
        },

after

        "program": {
                "instances": {
                        "program": {
                                "running": true,
                                "pid": 4904,
                                "command": [
                                        "\/usr\/bin\/program",
                                ],
                                "term_timeout": 5,
                                "limits": {
                                        "core": "unlimited" 
                                },
                                "pidfile": "\/var\/run\/program.pid" 
                        }
                }
        },

When restarting the app with /etc/init.d/program/stop and then /etc/init.d/program/start, the issue does not appear.
procd logs give me the following :

with restart:

2019-02-04T14:50:32.273940+01:00 procd[1]: Stop instance program::program                                            
2019-02-04T14:50:32.383913+01:00 procd[1]: Update service program                                                     
2019-02-04T14:50:32.385539+01:00 procd[1]: Update instance program::program                                          
2019-02-04T14:50:32.385539+01:00 procd[1]: running /etc/init.d/program running                                        
2019-02-04T14:50:32.389260+01:00 procd[1]: start /etc/init.d/program running                                          
2019-02-04T14:50:32.498445+01:00 procd[1]: Instance program::program exit with error code 15 after 48 seconds  <= program stops after the start procedure ?
2019-02-04T14:50:32.498445+01:00 procd[1]: Started instance program::program[6006]                                   
2019-02-04T14:50:32.507124+01:00 procd[1]: stop /etc/init.d/program running - took 0.118804167s

with stop and then start :

2019-02-04T14:54:34.193629+01:00 procd[1]: Stop instance program::program                                            
2019-02-04T14:54:34.271597+01:00 procd[1]: Instance program::program exit with error code 15 after 16 seconds        
2019-02-04T14:54:34.590466+01:00 procd[1]: Ping                                                                        
2019-02-04T14:54:39.596012+01:00 procd[1]: Ping                                                                        
2019-02-04T14:54:44.598687+01:00 procd[1]: Ping                                                                        
2019-02-04T14:54:45.251411+01:00 procd[1]: Create service program                                                     
2019-02-04T14:54:45.251411+01:00 procd[1]: Start instance program::program                                           
2019-02-04T14:54:45.251411+01:00 procd[1]: Started instance program::program[6269]                                   
2019-02-04T14:54:45.255180+01:00 procd[1]: running /etc/init.d/program running                                        
2019-02-04T14:54:45.269798+01:00 procd[1]: start /etc/init.d/program running                                          
2019-02-04T14:54:45.491149+01:00 procd[1]: stop /etc/init.d/program running - took 0.231052709s

It looks like the program takes too long to stop and procd has trouble with this ? how is procd handling restarts ?

thanks !