It could be related to flash not be enabled or being blocked, there a quite a lot of posts on this type of problem if you search, for example - Hyperion Calculation Manager Graphical Interface Issue
Only time I experienced this the nightly backup had gone 'rogue' and was still running, it might be worth a quick check via 'Application Management' - Migration Status report to ascertain if this is your issue, as if it is then it urgently killing before continuing with any kind of transactions...
Otherwise, try a restart of your services.
If you version if not 126.96.36.199 check this Calculation Manager Rules Designer is Not Displaying the Rules in Graphical Mode (Doc ID 1479466.1)
It its 188.8.131.52 check this Graphical Flow Chart within Calculation Manager Rules Designer Keeps Displaying as "LOADING..." on 184.108.40.206 with IE11 (Doc ID 2002751.1)
Make sure that Flash Player is enabled.
If it was enabled and the issue persist then Un-install and Re-install the latest version of Flash Player.
If that does not help then use the below link and go to the bottom of the page where it says "Still having problems?" and use the option "Flash Player for Internet Explorer - ActiveX" to install the latest version of Flash Player.
Clear the cookies and re-open a new session of IE.