There are several weird issues when working with DataTable containing a Class as a variable type.
Create a structure containing a variable that has a type of “Class” of some Blueprint type
Create DataTable based on this structure
Create a new Row and try to set variable to some class.
For example we tried to create DataTable which has a variable of type ClassOf:“Weapon Blueprint”. Then create rows that had various weapons set like “Pistol Weapon Blueprint”, “Rocket Launcher” etc. We got either random crashes or random errors in Blueprints like “PROTO_C_Character is not based on Character_C” even, if all we did was simply creating said DataTable. Basically it looks like creating DataTable with class as a type is messing completely Blueprint system and all Blueprint types.
Unfortunately I couldn’t reproduce it in simple project, nevertheless I’m sending you simple project in which you can see some odd behavior that could potentially create problems in bigger projects. Just copy files to a /FirstPersonBP/ folder in FirstPerson sample project.
There are few things you can check/test: Change type of variable in structure to something other than “TestBPClass2”. Then when you try to edit DataTable, you can try to select some classes. It can result in displaying empty field like on screenshot bellow (DataTable does not properly gather possible classes).
If you don’t change anything and just load files I’ve attached, you will notice that you can’t select “TestBPClass3” in a variable despite “TestBPClass3” having “TestBPClass2” as a parent.
TLDR; We have crashes in our project, and odd behavior in simple project. See screenshot for issues.
I was able to reproduce the odd behavior you described (other actor and child weren’t listed) using the assets you attached. However, I was trying to get the same results in a clean project with newly created assets but I haven’t been able to do so. What were the exact steps you used to get the actors to stop being displayed in the Struct dropdown?
I believe that problem is with order in which assets are loaded into engine, and this order is determined by order of files on drive and/or name of the assets. So steps really don’t matter.
However the easier/faster way to get one of the bugs I reported above:
Create Blank Project
Create Blueprint based on Actor, named K1. Open BP, Save. Close BP editor (not main editor!)
Create structure named M1. Set type of default variable to a “Class of K1”. Save structure. Close Structure editor.
Create Data Table based on M1. Add Row. Set variable in a Row to a K1 class. Save. Close Data Table editor.
Create BP named K2 based on K1 BP. Save. Close.
Open Data Table for M1. Change variable from K1 to K2.
Now value in Data Table row should disappear (will not display K2 despite of being set to K2).
Thanks for taking the time and adding the additional steps. I was able to reproduce these in a new blank project so I have created 2 bug reports.
JIRA UE-29837: Data Table row will reset to None if Child Actor is selected
JIRA UE-29835: Child Blueprint isn’t listed as a option for a variable inside of a dataTable until the Child BP is re-saved
Out developers will be investigating these further and we will post here with questions or updates as we have them.
If you come across any other bugs dealing with Data Tables, please make a new report in the Bug Report section; make sure to reference this post and include as much info as possible.
