If you are editing the style of a button or link that has combo-classes attached, there is no way to edit any other state “hover/visited/etc” of the single-classed element. Well, not without going to where a single classed element exists and editing the alternate state there, instead (the only workaround).
It’s not a bug, per se, it’s more like a fringe case that isn’t allowed for, but I see it happening frequently if you create various different buttons or links that utilize the combo-class feature.
Here is a similar but different case:
The workaround by @vincent works here, too, but bolsters the case that this is a common UI issue that could stand to be updated when resources are available: