Issue is with latest version.
For a quick fix until the developers of RealUI fix this just do the below:
1. Download RealUI-8.1_r20f (it's locasted in the archives)
2. Open the package, I use winrar for this.
3. Navigate to RealUI\Interface\AddOns\nibRealUI\Core\
4. Now copy the Fun.Lua file to your wow installation and replace file when asked (e.g. C:\Program Files (x86)\World of Warcraft\Interface\AddOns\nibRealUI\Core\Fun.Lua)
Enjoy quick fix until devs look at this
