Box not allowing live collaborative work

After our team upload a word document to box, when the client goes to open the file they are met with this message.

Is it a requirement for our client can work on the document live, not just in reading view or in the desktop app. Please can you explain why this is happening.

The document is not set to read only and previous documents uploaded the same way have not had this issue. When the file was downloaded and reuploaded on to Box it was fully functioning again. 

The user does have permission to the file and there were no restrictions placed on the file. The user opened the file from Box.com. The user could download the file and open it in the desktop app however that is not the preferred way for collaborative work.

Further investigating found that copying and pasting the whole document into a new word doc. and then uploading that worked. Something odd to note was although all the visible content remained the same, the copy and pasted document was slightly smaller in size (22.3KB instead of the original 28.5KB).