Can't edit TMap variable?

I was tinkering with the new 4.14 preview 2. I was able to turn on TMap and TSet and added a new variable to a blueprint class in Starter Content and it compiles okay.

However when I try to edit its default value (add an element to be more specific) the editor just crashes and says:

Assertion failed: PropertyFlags & CPF_HasGetValueTypeHash [File:D:\Build\++UE4+Release-4.14+Compile\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Property.cpp] [Line: 1234] 

Nor can I do anything with it except setting. Can’t get value from key (or can’t find the function to do so); can’t set new elements in runtime (or can’t find the function to do so…)

Is this normal/intended or just a bona fide preview, so all i can do is get a view of it? Any thoughts?

What are you using for the key?

just default types, bool int and float, I’ve mixed the 3 in several ways.

Anyway, I just realised that in Editor Preference->Blueprint Editor->Experimental, where I enabled Tset and Tmap, it says “(incomplete, non-functional)”… Guess they weren’t joking:D

The release version still crashes and has the same incomplete, non-functional text… Has anyone else tried? Did my update fail?

Tmaps and tsets are experimental and not functioning currently unfortunately

Shame that the release documentation doesn’t indicate this at all. It’s the only reason I installed 4.14