I’ll wager one frosty beverage that this isn’t going to work out well for you.
The “ground” terminal on the typical single-output bench supply has nothing to do with the “and ground” part of “±12V and ground”
That “ground” terminal on that sort of supply is connected to the device chassis, the third prong on the AC power plug, and (if your building is wired properly) the dirtball spaceship. It has no direct connection to either output terminal of the supply, thus cannot sink/source current from either.
The “and ground” part of “±12V and ground” means a midpoint between two points 24V apart, capable of providing a path for current flow through either of the remaining two terminals. The board itself doesn’t care a bit which (if any) of the three are connected to the dirtball spaceship.
In the lab, such a source is usually created by using two single-output bench supplies connected in series, or the two (isolated) outputs of a dual-output bench supply connected in series.
See also this post for further illustration of the topic.