Is this something you can reproduce always?
Because it seems to be working fine for me with your game v0.26.8.20 and our RC5.
Is it normal that if I modify the image and save it, then the game shows the "COMPILING" message and reloads?
Anyway, before reloading I can see the background image is tiled correctly.

The current game version doesn't have image reloading implemented for NoesisGUI yet. It simply invokes full reloading (scripts + UI, with purging our NoesisTextureProvider's cache). That's why you cannot reproduce the issue.

If you want to check, please use this Editor build https://www.dropbox.com/s/ad95yu22vt6orqr/CryoFall_Editor_v0.26.8.27_NoesisGUI_3.0.0rc4.7z?dl=0 (built with RC4)
It also doesn't have hot reloading for image file changes. But it's using RaiseTextureChanged for each image that could not be provided to NoesisGUI instantly through LoadTexture method of TextureProvider's implementation. (All of them are cannot be provided instantly in this build. So I've implemented async texture loading for NoesisGUI TextureProvider)

Also, GetTextureInfo method of TextureProvider's implementation will provide width=0 height=0 for missing files and width=1 height=1 for existing image files that are not yet loaded in the cache (if they're loaded it will provide actual width and height).

So far it works perfectly well for every image used in the UI except the ImageBrush x:Key="WidgetBackgroundImageTexture"

I've verified that for "/UI/Images/Backgrounds/WidgetBackground.png" after RaiseTextureChanged NoesisGUI does request the GetTextureInfo() method (and collects result with width=8 and height=8) and then does LoadTexture() for it. The texture is loaded properly (it was magenta texture initially, and I clearly see it's no longer a magenta texture), but the tiling is not updated.

Regards!

Please check the main menu. There is another but similar issue when the texture has incorrect rendering (incorrect stretching) in Image object after reloading. I've tried manually setting Image width or/and height but it doesn't help.

<Image Source="/UI/Images/Logo/logo_cryofall_128.png"

Grid.Column="0"

Margin="10,5,40,5"

Stretch="Uniform"

SnapsToDevicePixels="False" />

Here is the screenshot:

Screenshot at 02-12-43.jpg (17,681 bytes)   

Screenshot at 02-12-43.jpg (17,681 bytes)   

How should it look:
(if you use Ctrl+F5 it will look this way as our texture provider will not use reloading and instantly provide the proper texture size by using the cached DX Texture2D object)

UPD. I've checked the whole game and there are no other cases of this issue. Even though we're using Image Stretch in several other places.

Screenshot at 02-15-38.jpg (32,825 bytes)   

Screenshot at 02-15-38.jpg (32,825 bytes)   

No priority with this as I believe it would be not right to report to NoesisGUI 1x1 size as it doesn't result in the correct layout immediately which might be essential in some cases (it's weird when for example the main menu layout is changed as the images are loaded asynchronously).
When providing actual size to NoesisGUI it works properly and likely will not cause any other issues. Calculating an actual size is a slight and reasonable overhead and it's anyway much better than how it was before NoesisGUI supported async texture loading with our texture provider.

Regards!