If it occurs, select View > Window Layout > Normal menu item, or press Shift + Alt + L key. The window layout will be reset and missing windows will be back.
If the issue still remains, try below steps:

1) Quit EDIUS.

2) Press Win + I key to open Windows settings.

3) Select System > Display.

4) Layout screens horizontally like below (order of display number can be different)

5) Start a project and confirm if EDIUS windows appear in second display.

6) If resolved, keep to run EDIUS and rearrange display layout in Windows settings.

7) Go back to EDIUS then select View > Window Layout > Save Current Layout > New.

8) Type layout name then click [OK].

9) When the issue reocccurs, select  View > Window Layout > Apply Layout > {REGISTERED LAYOUT NAME} to recall your original window layout.