I have the same issue. Mine is saved as I DON'T KNOW AAA everytime I start my sever.. And when I forget to change it, it looks funny :c
Hopefully a solution will come forth.
I got a solution, this used to happened me too, but I made it that my server has a new welcome message.
I mean, I cant put different welcome messages saving, but I can change it so It says a decent welcome message.
Now go to Blockland/config/server/prefs.cs
Make a copy for the prefs.cs if something goes wrong.
What I do is change name of prefs.cs to prefs.txt, then I search for the welcome message option, and change it.
Now when you change welcome message make sure that you put '' at the start of the message, then when you finish it put ''; at the message, Colors do work.
Example:
''<color:00FF00>Welcome to my server %1.'';
When you finish it, chance prefs.txt again to prefs.cs and move it to Blockland/config/server
If everything is alright, it should look like this ingame
Welcome to my server Checko2100.