UPDATE 8:
Managed to fix it. Seems to have been a complex problem. Things I have done:
First:
Created a game singleton class with asset id reference array containing reference of all ActionGeneric children. Set it in defaultengine.ini. This seems to solve the issue of assets not loading in time on editor startup.
Second:
Recreated original GetActionBPClass graph (not the function itself). Got rid of casting to Owner to WorldObject (not needed and was breaking things, possibly introducing reference loop). Recreating the original function, even with these changes was not possible: it would still break putting function return result to PLACEHOLDER-CLASS. So I put the graph in the Initialize function instead. It ends up being a bit bloated, but works fine.
Third:
Removed Initialize call from WorldObject and put it on BeginPlay of the component instead. Once again, a potential contributor cycled reference.
Fourth:
Beautify pass - comments and straightened links. I am sure it helps. 
Have tested mutliple times with recompiling, resaving, restarting the editor. Seems to hold up nicely. I am sort of glad 4.12 came along as it made me to properly fix a nasty bug that laid dormant for more than 4 months.
