We are currently running on UE 4.12.4 and we have an issue in one of our UMG Blueprint Screens where at randomly times when we scroll through our screen, certain widgets both inside the scroll box and outside of it, seem to get their rendering information broken for a single frame, causing them to be drawn over most of the screen in a distorted triangle.
For instance we have a button located in the top right of the screen and sometimes as we scroll, it suddenly get rendered from its anchor point, to near the opposite side of the screen, but as a triangle instead of its square size.
This behaviour does not occur every time we scroll, but when it does occur it seems to happen no matter how fast we are scrolling.
I was thinking it might be related to this bug Why do UMG Widgets Flicker on iOS/Why are pictures blurry on iOS? - UI - Unreal Engine Forums
This only occurs on Metal, as our project is setup not to run without metal. The widget itself consists of a few buttons that lie outside the scroll box, and then a scroll box which takes up about 66% of the screen, which contains a Uniform Grid Panel, which then contains a whole number of Vertical Boxes, each containing an image and text.
Like the other bug we do use the Canvas HUD system as well. I will try and get a video of the bug itself, as capturing it in a screenshot is next to impossible.
My first question is did the first bug in question get fixed and is it possible to try that?
What else can I provide to help track this down, as it is a bug which is holding back our release and Apple really want it fixed.
Edit: I have only managed to repro this very very rarely in a new project. It could be that the lower the frame rate is, the more often it occurs. I created a HUD which just draws a texture, and then a umg widget with a scrollbox which contains about 30-40 image widgets in a 4 column uniform grid layout. With this I can get it to happen only once after launch, on the first scroll only. It doesn’t happen 100%. I am going to do some more experimentation.