The username atapon_los cannot search any reviewers

Hi Bitbucket team,

I have create the user atapon_los from member in team. I had been give all the permission same with another user. He can search reviewers and can do the pull request normally. Until Thursday, APR 25, He cannot search any reviewers on input box. I'm not sure, What is a change or maybe some setting on my site had been change? I try to looking for a while, but nothing found. So could you please help me to take a look on it?
Attachment file please find more information.

Thank you in advance.