You can already see above that the padding is getting applied, but I can also confirm if I inspect it that the control value is now being rendered without quotes, which is why it’s now working when it wasn’t before. (Edit: ignore the actual values here that don’t match up with the controls above, I was working in multiple tabs and didn’t refresh the page before taking the screenshot, but you get the idea)
There’s some new syntax that’s being introduced that will allow people to refer to individual values when a control contains multiple values. For example, in the case of the dimension control, we might want to refer just to the top dimension or just the selected unit instead of referring to the whole value as I’ve done here with $dimensions_control. That should be added to the docs in the coming days, but from your original post, it doesn’t sound like that’s your issue.
It sounds like you have a number control and you’re trying to append something (like “px”) to the end of the value of your number variable. That’s not really an L&L question and is more of a SASS question. This article seems to suggest that you can just append stuff with +, but my area of expertise is L&L, not SASS, so maybe someone else can chime in with recommendations there. But at the very least I can confirm that rendering new control values in SASS using $my_control_name seems to be working as expected now.