In LinqPad: "Query completed successfully with warnings"

You should get a little yellow warning triangle at the start of the line(s) that contains the warning.

And when you hover over the triangle, it show display what the actual warning is.

See screenshot

As of V5.36.03 Premium I see the triangle, then I don't.

In short the triangle disappears the second time you execute a query if no code changes are made.

I have reported a bug through LinqPad:

Yellow warning triangle disappears, when [F5] is hit twice in a row with no source code changes.

The status bar continues to show Query completed successfully with warnings.

After a change is made, the triangle reappears for the next run only.

Sample code is trivial:

void Main()
{
    var v = 1;
}

Problem was found in a longer useful query.