Email Id's to notify not working on client side

Email Id's to notify not working on client side

Greetings, 

I have been having a problem regarding a field called Email Id's to notify which is really odd. I have implemented this field on requester side and whenever a requester clicks on it, no emails are shown and an error message which says " Loading failed" Appears, but on the other hand this field works as intended on technician side and I see every associated emails on imported AD users. I will appreciate it if anyone helps on this matter. 

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