:terminal view won't update without additional keypresses/mouse movement

[amadeus]

Not sure if this is a vim or macvim issue, but it appears that when I use :term on the latest MacVim built from this repo, the terminal buffer won't update until after I press a key or move the mouse, so it's always continuously one update behind.

Not sure how obvious it will be in this example video:

example

[chdiza]

I see the same problem.