Metricbeat MSSQL - Secure pwd keystore not working

Hi Everyone,
I would like to connect the Metricbeat MSSQL using a secure password into a keystore.
I have created a keystore, define the password into mssql.yml as described below:

metricbeat keystore create
metricbeat keystore add MB_PWD >> set the password

mssql.yml:

> - module: mssql
>   metricsets:
>     - "transaction_log"
>     - "performance"
>   hosts: ["sqlserver://MYSQLXSERVER/SQLINST:1439"]
>   username: metricB
>    password : "${MB_PWD}"
>   period: 10s

the error received into the metricBeat log file is:

{"file.name":"instance/beat.go","file.line":1307},"message":"Exiting: 2 errors: host parsing failed for mssql-transaction_log: missing field accessing '0.password' (source:'C:\\Program Files\\metricbeat\\modules.d\\mssql.yml'); host parsing failed for mssql-performance: missing field accessing '0.password' (source:'C:\\Program Files\\metricbeat\\modules.d\\mssql.yml')","service.name":"metricbeat","ecs.version":"1.6.0"}

It Works When i use the same password in CLEAR into the mssql.yml file

Could you please help me with that one?

Thank you.
Regards,
giomlux