UE4 Meta specifier "ExactClass" not working

I have a UDataAsset A and a UDataAsset B that inherits from A.

In B, I want to have a reference to A. Since B inherits from A, I could choose DataAssets from B, which is unwanted.
I’ve looked into specifiers and found out that “AllowedClasses” and “ExactClass=true” should limit the drop down results. ExactClass is supposed to limit the results to the classes specified in AllowedClasses, and only them (excluding children), according to the docs here:

However, I have found that this does nothing to filter out children classes. I can still pick objects of the children class B.

Am I missing something or is that a bug?

Try to remove unreal prefixes from list of your classes like so:

meta = (AllowedClasses = "DataAssetA", ExactClass=true)

as you can see you omit unreal prefix from class be it “A” for actor based classes or “U” for UObject derived classes. If you have more classes to limit object picking then just use coma and add them inside double quotes as well. Eg. :

meta = (AllowedClasses = "DataAssetA,DataAssetXX", ExactClass=true)