Attachment name changed to untitled in outlook

Hi,

Anyone who know some emails attachment file name changed to untitled when they open it with outlook desktop for M365, those mails sent by internal invoice system sent mail with attachment. 

In this case do you know how to resolve it in outlook side? 

Even if I searched that case, it looks related to rfc protocol, and file name length.

But I don't know what is true, how to resolve it, 

Please help me~