Compiling a widget causes a widget component using it in the game view port or a blueprint viewport to stop rendering. Moving it afterwards will sometime make it start rendering again.
You can also change some variables on the widget component to try and get it to start drawing again.
This bug doesn’t happen on 4.16 but happens on a fresh project on 4.17 (Flow version)
I also might have found a related bug but a widget that I had updated with a new image didn’t show up with that new image and so it was out of date with what I was seeing in the widget editor, no matter how many times I compiled it or re-added it.
A third bug is that when removing the currently assigned widget from the widget list drop down on a widget component, it wont actually remove it from the blueprint view port editor. It is still there.
I’m going to test a clean version of 4.17.1 rather than this nvidia flow version to see if it still happens.
Tested a clean project and 4.17.1 and the same bug happens.
To test Make a clean project Make a widget, add a few objects to it. Make a blueprint, add a widget component. Select your new widget. Switch to the editor for your new Widget, press compile (even if no changes). The widget will disappear. Move it to bring it back.
Next try clicking the X to remove the widget class, notice it will still show your widget.
As for the out of date widget bug, I don’t know an easy way to reproduce this.
Another bug I’m experiencing with widgets is when you press draw at desired size they disappear forever, and you have to delete then add it again to see the widget again.
The out of date bug (2nd) is actually the widget component not calling “PreConstruct” so some of the settings I used that are assigned by variables on the widget don’t get set in the editor viewport.