Conversations Thread not work

Hi, After I tried to click Show> conversations on the view of inbox.

I found some mail convsersation show

“This Conversation Thread is Incomplete”.

Anyone face it before? May I know how can check this problem to fix it? Many Thanks.

Subject: Have the same issue

I have the same issue… But I can see that the problem concerns only messages from one company.others work fine as threads.

Have no idea how to solve

Subject: The problem still exists with Notes 9