This continues to be an issue on OBS Studio version 27.2.4 (x64), happening with regular reboots, and may have something to do with Display Port connections but I really don't know.
My PC has 3 monitors.
According to Windows, Display #1 is my main, center display - an Ultrawide HD connected by Display Port.
Display #2 is also connected by Display Port and located to the physical-left of my main display.
Display #3 is connected by via HDMI and on the physical-right of the main display, rotated 90 degrees to make it vertical.
When rebooting, Monitor's #1 and #3 are often switched in my scenes, and I must re-select their numbers in OBS.
The OBS Display numbering does NOT Match Windows, and I believe is part of the issue.
Windows numbers the monitors, left to right, 2, 1, 3.
OBS numbers them 1, 2, 3.
I've just rebooted to try and reproduce the issue and it did
not recur
this time, but happens frequently and as others have stated, is a major hassle, forcing re-assignment of display sources prior to each and every stream.
Here are multiple examples of the Display initializations from within the OBS logs at different times, demonstrating the differing-assignment and detection order:
Code:
12:31:05.288: display: 1 (1920x1080)
12:31:05.288: cursor: true
12:31:05.288: method: DXGI
12:31:05.304: [duplicator-monitor-capture: 'Monitor: Middle'] update settings:
12:31:05.304: display: 2 (3840x1600)
12:31:05.304: cursor: true
12:31:05.304: method: DXGI
12:31:05.306: [duplicator-monitor-capture: 'Monitor Right'] update settings:
12:31:05.306: display: 3 (1080x1920)
12:31:05.306: cursor: true
12:31:05.306: method: DXGI
------------------------
09:28:50.330: display: 2 (1080x1920)
09:28:50.330: cursor: false
09:28:50.330: method: DXGI
09:28:50.330: [duplicator-monitor-capture: 'Right '] update settings:
09:28:50.330: display: 3 (3840x1600)
09:28:50.330: cursor: true
09:28:50.330: method: DXGI
09:28:50.331: [duplicator-monitor-capture: 'LCD Left'] update settings:
09:28:50.331: display: 1 (1920x1080)
09:28:50.331: cursor: true
09:28:50.331: method: DXGI
------------------------
10:01:02.118: display: 2 (1080x1920)
10:01:02.118: cursor: true
10:01:02.118: method: DXGI
10:01:02.122: [duplicator-monitor-capture: 'Monitor: Middle'] update settings:
10:01:02.122: display: 3 (3840x1600)
10:01:02.122: cursor: true
10:01:02.122: method: DXGI
10:01:02.123: [duplicator-monitor-capture: 'HUD: Monitor Left'] update settings:
10:01:02.123: display: 1 (1920x1080)
10:01:02.123: cursor: true
10:01:02.123: method: DXGI
-------------------------
13:11:01.542: display: 1 (1920x1080)
13:11:01.542: cursor: true
13:11:01.542: method: DXGI
13:11:01.548: [duplicator-monitor-capture: 'Monitor: Middle'] update settings:
13:11:01.548: display: 3 (1080x1920)
13:11:01.548: cursor: true
13:11:01.548: method: DXGI
13:11:01.551: [duplicator-monitor-capture: 'Monitor Right'] update settings:
13:11:01.551: display: 2 (3840x1600)
13:11:01.551: cursor: true
13:11:01.551: method: DXGI
-------------------------
10:36:46.391: display: 3 (3840x1600)
10:36:46.391: cursor: true
10:36:46.391: method: DXGI
10:36:46.394: [duplicator-monitor-capture: 'Monitor: Middle'] update settings:
10:36:46.394: display: 2 (1080x1920)
10:36:46.394: cursor: true
10:36:46.394: method: DXGI
10:36:46.394: [duplicator-monitor-capture: 'HUD: Monitor Left'] update settings:
10:36:46.394: display: 1 (1920x1080)
10:36:46.394: cursor: true
10:36:46.394: method: DXGI
Hopefully these logs provide an indication, but can produce more if needed.