Mentioned in this comment.

Indeed, it does:

I don't know if it's meant to be like this. There are three metrics there: Line, Character and Column. The Column metric is hidden unless it differs from the Character one.

It's not really clear what are the designed scenarios for that.

Note, C# does the same.

So, I see a few explanations to what is going on:

1. It's by design
2. It's a bug in Roslyn
3. There is a setting for this which neither F# nor C# utilizes

Further investigation is needed.