It's not enough to just look at the amount of your refund. There are a lot of complicated interactions among various entries on your tax return. The capital gains should appear on Form 1040 line 7, or be added to any amount that's already on that line. That should increase your total income on line 9 by the same amount. To figure out what's going on, you have to look at everything after that, from line 10 through line 38, to see what else is changing or not changing, and by how much. If an amount changes that comes from another form or schedule you might have to look at the other form or schedule to see why it changed.
If Form 1040 line 7 does not change when you enter the capital gains, then either you are not entering the capital gains correctly, or you do not have the amount of gain that you think you have.
Also, you said "Our gross income will exceed $350,000." You can't draw any conclusions about what will be. Your comparison before and after the capital gains are entered is not meaningful unless you have already entered everything else. To make a valid comparison the return has to be complete except for the $10,000 of capital gains.
