This is a wiring conflict, common with heat pump systems. The O/B and W terminals are likely incorrectly configured.
For heat pump systems, check the wall plate wiring. Verify there is not a wire attached to the W terminal on the wall plate. If there is a wire in W, it's telling the system to engage auxiliary heat (like electric strips) which can run simultaneously with cooling, causing the conflict. That wire may need to be moved to the O/B terminal or another terminal based on your old thermostat's configuration.
If that didn't work, the R-switch position might be wrong. The R-switch on the wall plate must be set correctly for your system. If you have only one R-wire (R, Rh, or Rc), the right R-switch must be in the UP position. If you have two R-wires (R and Rc), the right R-switch must be in the DOWN position. An incorrect setting can scramble system signals.
This is a scenario where referring to the picture of your old thermostat's wiring is critical. If you're unsure, shut off power and call 1-855-733-5465 for a pro.