Personally I believe it is a problem with hot reload, yes. I’ve noticed that this used to happen to my Blueprints that inherit from a C++ class all the time whenever I added a property, added a method, changed how a property was exposed, etc.
It’s kind of annoying, but a “workaround” seems to be to close the editor when you want to change something, make your changes, then re-launch the editor by going to “Debug > Start Without Debugging” or by pressing Ctrl+F5 within Visual Studio.
Yeah, it can get pretty frustrating to have to re-set properties in the editor. I haven’t had that happen to me since I started closing my editor any time I need to make a code change, though.
I have a Blueprint UserWidget subclass of a C++ widget.
I have a bunch of properties marked EditDefaultsOnly or EditAnywhere, and I’ve set up some of them to point to textures, have different values for floats etc.
The problem is, sometimes when I re-open the Blueprint UserWidget, all of these properties have been reset to their default values. Why would this be? I use Hot Reload sometimes, would that cause it? Has anyone else seen this problem?
Thanks for the feedback, Richard. I swear I saw this happen when I changed stuff in the .cpp file, or when I changed unrelated files.
But I can see how hot reload might cause it to happen…
Yes its a hot reload problem, this always happens when you change the layout of a class or struct (adding or removing properties). I always restart the editor when i change a layout. Adding functions or changing code doesnt matter. This is suposed to be fixed in 4.20. Also make sure you restart and dont change any values in the bp first or youre royally ■■■■■■, the restart wont help you then, ive been there 
I’ve just done some test, Its fixed in 4.20!