The reproduction requires additional conditions:
• Decimal separator set to comma on your OS (default settings for languages such as German)
• .NET Scripting Runtime is set to 4.x (3.5 works fine)

To reproduce:
1. Make sure the above conditions are met
2. Open any project with ShaderGraph set up
3. Create a new Shader Graph of any type
4. In ShaderGraph window, Create a property of type Vector1
5. Set the mode to Slider and change Min or Max value to a float (ex.:0.1)
6. Create any node

Result: pink textures are shown in Node preview

Reproduced in: 2018.3.3f1
Could not test on any 2019 releases (Shadergraph 5.x issue), due to another bug (case 1111305). If the bug is fixed, information will be updated

Note: After saving Asset, Shader Inspector window will also state that "Shader is not supported on this GPU (none of subshaders/fallbacks are suitable)"