I recently upgraded to Horizon Client 5.3 on my mac to connect to work.
But immediately found that when using the new client, there is no screen update after mouse click.
If I switch between apps locally and and return to horizon client,
it shows that my remote PC received the mouse click and reflects the updated screen,
but Horizon does not repaint the screen when I click otherwise.
I downgraded to 5.2.1 to get working again,
and as test I reinstalled 5.3 again 2nd time to confirm the same result.
If it helps diagnose:
I’m using an older iMac from 2009, running High Sierra 10.13.6 (the latest supported on this mac)
And a magic mouse (bluetooth)