Details
There is no drop down list available for keywords defined in the propseed.txt file.
Solution
This is a known behaviour. If you edit the propseed.txt file and change "Keywords" to "Keyword" (no "s" on the end), this then should work as expected in both Property Manager and File Properties.
Hardware/Software Configuration
Platform: INTL64
OS: window
OS Version: 1064
Product: SOLID_EDGE
Application: APPLICATION
Version: V110.0
Function: PROPERTIES
Ref: 001-8828955