Have you selected the Edit-In-Cloud link and received a blank AceOffix pop-up window like the screenshot below?

Do you see the Document you opened for editing in UCM, opened in Word instead of AceOffix?

This issue can be easily resolved by simply updating a Compatibility option in you computers version of Microsoft Word.

All you need to do is open Microsoft Word (as well as Excel and/or PowerPoint if you use AceOffix to edit any of those file types as well), go File in the top left corner of the page, then to Options (1) in the bottom left. From the Option pop-out, switch the When using multiple displays: setting to be Optimized for Compatibility (2). Then select OK (3) to save.

It is recommended that you close out of all AceOffix and Word windows prior to trying to Edit-In-Cloud again. 

If any issues still occur, try a full system restart and the solution should be correctly applied at that point.