archived items return a blank body

HI,

we have some user reported that there are some archived email show blank body in their value in outlook. he also check the itme in weblink and still the same. we find the those emails which mark black also come from same coversation (same email reply or forward ). 

We are using enterprise Vault 12.3 and Exhcnage 2013.

may i know how to fix this issue or retrieving the email?

Thanks