Replied or Fwd email has content replaced with 3 'Chinese-like' Characters

Hi,

This has just started happening to some emails.

If I fwd or reply, all content  is stripped out including attachments and the Anti-V stamp and replaced with 3 chinese looking symbols.. That's it, just the symbols and nothing else.

The mail looks fine before I send but once sent both recipients and my sent box have the same mail. 

If I start a new mail and copy the contents it also happens.

Anyone have any ideas or seen this before

I'm on 365, it's happened on 2 diff accounts and on Win 10