I'm using a fresh installation to test using latest version of CMSMS (2.2.21). 
I added all the most recent updates of the required modules, Products, Orders,
Cart2, FEU. Latest CGExtensions used (1.65.2). Promotions module installs
without issue, is set as the required module in CGEcommerceBase (1.8.10).

Any attempt to create a new promotion results in a blank page.

Rolling back the CGExtensions from 1.65.2 to 1.62.8 allows me to create a new
promotion, the database reports the version is newer but it works.

I'm not able to select a Product category or hierarchy as an option when setting
the conditions of a promotion, a related issue? The result breaks the website
resulting in a blank page being displayed.

Is there a setting required with the newer CGExtensions in the config file?