Popup contact info box can't be dismissed when To/Cc/Bcc clicked

OnePlus 10 Pro,
Android 12,
K9 v6.507

When composing an email, the “popup” contact details box that’s displayed when clicking in the To/Cc/Bcc area can’t be dismissed to allow further addresses to be appended.

When composing an email, I as example add 2 initially addresses in the To: box. When focus is moved to subject/message, the To: recipients list contracts to show “email address” +1.

The action to append further addresses in the To: box from this point is unclear and non intuitive.

  1. Clicking the down arrow shows cc/bcc boxes rather than expanding to show the full recipient list.
  2. Clicking within the To: box displays a contact information popup. This can’t be dismissed to allow further addresses to be added without deleting the existing addresses.