Client had the exact issue and was able to resolve by downgrading Office to previous update level.  As they're using Office 365, they followed the instruction within the following link:

https://support.microsoft.com/en-us/help/2770432/how-to-revert-to-an-earlier-version-of-office-2013-or-office-2016-clic

This new Sage 300 FR doesn't use Excel: http://www.dingosoft.co/frs.html It's developed in the Sage 300 SDK and uses Crystal - just like every other Sage 300 report, so may be a better alternative to downgrading Office. Also, the statement designer is a LOT easier to use. 

We've found that for Excel 2016 version 1706.8229.2103 works and 1707 breaks FR.

Sage has a fix available for this issue, for versions 2016 and 2017, in KB 85837. 

But not 2014?

Still can't use the Statement Designer as nothing seems to be appearing when clicking on the FR View nor the FR paste!

2014 is a retired version as 2018 is out. 

Same problem here, it's not working in the statement designer screen which is where I only operate and all my clients operate.

KB 85954 addresses the FR View/FR Paste issues in Statement Designer.

https://support.na.sage.com/selfservice/viewdocument.do?externalID=85954

KB did not work for my client using 2016 on a TS client

...and we have some happy clients now! I

Did you reboot the TS? The two clients that had the issue were local installs...