DIAGNOSIS You're expecting a cold brew, but the Over Ice function is designed differently. It brews a concentrated hot coffee directly over ice to chill and dilute it instantly. If the ratio is off, you get melted ice and weak coffee.
FIX The key is more coffee and less water in the recipe. 1) Use the Over Ice brew size (not Hot XL). 2) Pack the brew basket with about 25% more grounds than you would for a same-size hot cup. 3) Fill your cup with ice first, all the way to the top. The machine's cycle is timed for a full cup of ice. If you're using a travel mug, you might need to adjust the amount of ice down slightly.
IF THAT DIDN'T WORK Make sure you're actually selecting the Over Ice function (the icon with the cup and ice cubes), not just using a small cup setting. The button backlight should be solid for Over Ice, not flashing.
HEADS UP The first few seconds of the Over Ice cycle might seem like it's brewing hot—it is. Give it the full cycle to finish. The result should be a chilled, not lukewarm, coffee.