Hang: Print mode with external monitor

When opening Print tab with external monitor (Philips 32" in portrait) Dorico hangs on a redraw loop. There are sometimes scrollbars appearing, sometimes dissapearing during this hang, but no interaction is possible.

Everything is fine without the monitor. Latest Dorico, Macos 10.13.3

Can you provide a bit more information? Is the Dorico window on the portrait display, or on your MacBook’s own display? I can imagine that if the window is on a portrait display, when you have both the left and right panels open, there is insufficient width for the print preview to appear. You might try hiding either the left or right panels in Print mode using Command-7 or Command-9 before you move the window onto your portrait display to see whether that allows Dorico to successfully create the print preview.

Dorico on external display 16:10 QHD. The tall aspect ratio seems to trigger a redraw loop.
There is both toolbars open, and Dorico visibly suffers, there are tiny redraws, that may be related to the shadow of the page or not. I barely can do anything in Dorico when this starts to happen. I can move the window, but not resize it etc. Beachball of death, and a restart after 5 minutes of waiting.

Right now I need to finish a big orchestral project as soon as possible, but I will resume testing next week, and get back to you on this.