What is all this extra space in the Picture-in-Picture window?

[tastapod]

I created a 16:9 virtual display with a single custom resolution of 1920x1080 and set it to appear on my main monitor (an older Samsung G9). The window appears but as you can see there is a large unused area to the right and below.

I can't seem to get rid of this by fiddling with the settings. If I resize the entire window it scales with a huge scaling percentage in the middle.

Help! What am I missing?

[waydabber]

Hmm. This is clearly a bug. Which app version and macOS version are you using? (UPDATE: OK, I see it's Tahoe and must be a 4.x app version - which should be fine) Does the image resize at all? Can you show me how the PIP is configured in the app menu?

[waydabber]

Also, are you maybe using an app or third party that moves, snaps, resizes windows in any way?

[tastapod]

I'm using Moom but it isn't resizing the window in any way. I have quit it for now.

OK more clues, and different (weird) behaviour:

I am extending onto an iPad Pro to use as a teleprompt (my reason for BetterDisplay in the first place, which is working wonderfully!). The iPad is called 'Tastapad'. I have a virtual display set up called 'Virtual - Tastapad' to stream to Tastapad, inverted horizontally to use as the teleprompt. This has been working fine!

I created a second virtual display to be the 16:9 target of a Keynote presentation, so I can record this display, my webcam and a mic. When I activate the 16:9 virtual display, it takes over the iPad (and runs off the side because the resolution is too big), even though:

• it is explicitly not associated with any device
• the 'Virtual - Tastapad' display is associated with the iPad!

So I think what is happening is something like this:

• The 16:9 virtual display decides to stream onto the iPad, even though there is no association and it is not set up for streaming.
• This continues even in picture-in-picture mode, so the virtual display is both in a window on my main display and streaming itself onto the iPad.
• The virtual display associated with the iPad isn't anywhere to be seen.

So the extra padding we're seeing occurs when the iPad resolution is bigger than the 16:9 virtual display even though they are nothing to do with each other!

The new weird behaviour is that the PiP display is now showing OK on my main display, but is also appearing on the iPad at 1:1 size until it gets cropped at the right and bottom edges. (The mouse pointer on the virtual display appears in both places.)

Versions:

• macOS 26.2 (fresh reinstall because reasons)
• BetterDisplay Version 4.1.1 Build 47018 ('You're up to date!')
• iPad Pro M4 used as extended display, using latest iPadOS

[waydabber]

Ok, so you are saying that you have two virtual screens and two streams and the stream is mixed up (one or both streams show the wrong source), right? If so, this is a known bug with Apple's ScreenCaptureKit. Sadly this is permanent, only a macOS reboot fixes it, when it's in this state. But I might misunderstand the issue. This might explain why you see a wrongly sized image (as probably the mixed-up source has different dimensions then what the app assumes to be correct).

[tastapod]

Not knowingly streaming, unless picture-in-picture counts as streaming. If so, then it sounds like this is the case.

So should I assume that I can't (reliably) have a flipped virtual display as teleprompter and another virtual display as a PiP screen?

[waydabber]

It should work (after a restart) but sometimes macOS's ScreenCaptureKit may fall into this "state" for some reason. This is a longstanding issue now, Apple did not manage to fix the problem so far.

[tastapod]

Thanks, I guess I'll mark your previous answer in case anyone else runs into the same problem.

[waydabber]

I am sorry about this problem. Did a restart fix the issue?

ps. I reopened this as others might encounter this issue as well, this comes up from time to time.