Outlook Mobile App not working through LTM

dears ,

i have confirmed exchange server 2016 manually in LTM , didn't used the iAPP , everything is working perfectly i mean the webmail and the computer outlook application and only outlook mobile App is not working.

we already allowed /Microsoft-Server-ActiveSync in the allowed URL list but still we are not capable of either receiving or sending emails through mobile app.

note that ASM is also enabled.