Reply header missing when reply or forward

I has been using Microsoft 365 on my Macbook Air since early this year. It has been working perfectly all this while until recently i found that sender's header missing when i reply or forward some of the emails.

Not sure what happens, it doesn't show something like following ( the header below the signature and line below )

Regards,

My name

________

From : xxxxx

Date : xxxx

To : xxxx

Cc : xxxxx

Subject : xxxxx

I had checked my Preference->Composing, both HTML and Plaintext are correctly selected with header.

Strange is only happens to some emails, not sure why. Any one experience before and can help?