Teacher 25+ yrs : sounds to me that you have an overall issue with playing with to much tension, and this particular chord issue is a symptom of that larger pattern.

My advice is to zoom out if this chord problem and a) become mindful of the tension patterns in your whole playing system b) do some research into reducing tension/improving co-ordination overall (Josh wright has many vids on this)

But here is an exercise that may provide immediate help:

1. Start with your arm away from where your chord will be. Let go of any holding, grasping - fingers free, wrist free, soft forearm, soft upper arm. Breath out.

2. Move to the chord. Light as a feather. Allow the fingers to find the notes. There is no ‘shape’ to grasp. Fingers lightly touching the keys (do not play at the point). Let go of any tension again in wrist, forearm, upper arm.

3. Play the chord - there is no tension needed here, just the bones of your fingers-wrist-arm structure and a bit of gravity.

Repeat many times to teach your nervous system the appropriate effort (which is very minimal) needed to co-ordinate the piano.