Sorry for being a late adopter/late to switch but for reasons like this we typically stick with versions we are fast with until we absolutely must switch and can learn the changes.
Have just started switching to 2019 (and realizing why I am slow to switch), is this a glitch on my end or something new in 2019 that you start the program or start a new file and you cant set the size of your first drawn geometry? Start SU, draw a rectangle, punch in the dimensions for the rectangle, and absolutely nothing happens. Immediately draw another rectangle or any other shape and its back to normal. Is there something foolish now where you have to establish a drawing plane? If so can this be turned off?
Loaded up 2018 and its as normal.