Up until the latest release of Illustrator, pressing Command-Return after entering a new height or width for an object in the Transform panel would scale it proportionately. This no longer works and pressing Return does nothing if any modifier key is held down. The same is true for holding Option while pressing Return (this used to transform as a duplicate but has not worked for a while). Having to manually turn on the link button or disable it every time is very tedious. According to your own reference pages for keyboard shortcuts in Illustrator it is meant to be working, but does not.

Mac OS 10.15.6, Illustrator CC 24.3