Basically the title, here is my config. 

{
  "Image URL": "redacted",
  "Fade-in duration": 1.0,
  "Fade-out duration": 5.0,
  "Delay after joining to create image": 0.0,
  "Delay after creating image to start fade out": 5.0,
  "Anchor min (left bottom coordinate)": "0 0",
  "Anchor min (right top coordinate)": "1 1",
  "Image transparency": 1.0,
  "Show multiple times?": true
}

Yes same thing happened with me. Ever since the recent Facepunch update (perhaps related to Unity 6 now being used) The fade-in and fade-out property element is stuck on the screen which basically make it unable for us to click on any other UI related element afterwards. The fix was for me to completely disable Fade-in Fade-out when showing images and just directly show them. I am working on trying to fix this, will let you know if ever I find some alternative.

Question, is this preventing players from clicking on the [TAB]>"Contacts", "Crafting", and"Clans" buttons along the top of the screen?  Are you certain that it is the Welcome screen?

Thanks