No response when drag pdf from external monitor to Designer

[WaveF]

I have an external monitor, and I am trying to drag PDF file into Designer, it should be a PDF dialog appear but there isn't, it seems to PDF dialod auto move far away from 2 monitors and NO WAY to bring it back, then Designer was hang in there, mac will play a sound telling me I have click a place outside the active window when I click anywhere, and press all keys in keyboard with not luck to close that hidden PDF dialog, I have to FORCE QUIT Designer to continue use it (can not save any opened documents).

This bug exists on macOS 10.15.7, Designer 1.8.6 and below, and only happen when DRAG PDF into app, it's no problem if use File Menu to open PDF. 

[MEB]

Hi WaveF,
I'm sorry for the delay getting back to you. I've been trying to reproduce the issue here but no luck. Can you provide a few more details about you setup please? Do you have a single machine for example a Mac Pro connected simultaneously to two monitors, a laptop connected to an external monitor, what? And where is the main application? On the primary or secondary screen? Are running Affinity in full screen mode, separated mode, regular windowed mode?

I've tried in several view modes, with the application on both the main and external screen, dragging the PDF's from the desktop to the other screen to the app window and even to the app icon on the dock and couldn't get the PDF import dialog get stuck. In all times except one, the dialog appeared over the Affinity app window. There's one case where it displayed on the other screen but i veneer got it stuck. Thanks