Has this been fixed in Vegas Pro 20? (i.e. screen capture works with NVIDIA GTX 1650 Ti)

Short answer is No. That's why it is in the deprecated features in 20.

Personally, I use Vegas Stream for my captures. And there are other options as well - such as OBS.

Has this been fixed in Vegas Pro 20? (i.e. screen capture works with NVIDIA GTX 1650 Ti)

I saw the same problems in older versions, but now in Vegas 20 it works without any extra's which you can try by using the Trial version for 30 days

I highly recommend using other software to capture your screen, there are good options out there. I have gotten VEGAS Stream to work if you have the Pro package.

I installed the trial version of Vegas 20 that includes Stream, but I have the same exact problem using Vegas Stream to capture my screen. In NVIDIA Control Panel, Setting Preferred Graphics Processor to the default NVIDIA (instead of the much slower Intel Graphics), Vegas Stream gives me the error FAILED OPENING DISPLAY 1). It opens and shows DISPLAY 1 (my laptop screen) just fine if I use Intel Graphics, but then I get jerky video captures that are missing frames.

Try capturing with Intel's Graphics Command Center instead. I think the laptop screen might be hard wired to the Intel igpu in which case the screen should be available to the Intel app regardless of the Nvidia Control panel setting. Also suggest setting Vegas video prefs and Windows display graphics prefs to Nvidia too.

Has this been fixed in Vegas Pro 20? (i.e. screen capture works with NVIDIA GTX 1650 Ti)

I saw the same problems in older versions, but now in Vegas 20 it works without any extra's which you can try by using the Trial version for 30 days

Here is the Vegas Capture from Vegas Pro 20 without any change in the default settings after installation on my laptop from signature. Sourcevideo in the program is a GOPro HEVC UHD 50p file, where I'm on my bike riding

Update: I upgraded Win10 Home to Win11 Home. Now Vegas (V18) Capture doesn't ever show my laptop's display as a source for capturing.

For V18 it is also possible to install Vegas Capture as a standalone by copy "C:\Program Files\VEGAS\VEGAS Pro 18.0\VEGASCapture" and paste it into "C:\Program Files".
If uou use the startpictogram out of C:\Program Files\VEGAS\VEGAS Pro 18.0\VEGASCapture to start it you can choose which (other than Vegas itself) GPU it has to start with.
On laptop I had to do this for a good working capture untill Vegas 20 came.

With my NVIDIA Control Panel program on my Win10 Home ASUS Zenbook Flip 15 laptop (4K display resolution), I can set Preferred Graphics Processor to Intel Integrated Graphics or to NVIDIA High Performance Processor (the default). If set to NVIDIA the Vegas capture window only shows one video source--the laptop's integrated camera video. If set to Intel graphics, it shows two sources--the integrated camera and the laptop's display screen. I want to capture video from my display screen, but using the Intel graphics option, the capture video is jerky and misses frames. Has this been fixed in Vegas Pro 20? (i.e. screen capture works with NVIDIA GTX 1650 Ti)

@Eugene-Beer Same on my Zenbook Pro 16x. I can also set the NCP to auto-selected in which case VP20 and VP19 Screen Capture records my desktop just fine. OBS Studio, btw, is not affected by the NCP setting and it works fine. Capture is apparently gone from recent versions of the Intel Graphics Command Center. However, if I install the Intel Arc app, I can capture with that. But I find recent versions of the Arc app a little too chatty to the point of annoyance for my tastes. So I removed it from my laptop. If VP18 no longer captures your desktop, I'd recommend OBS Studio as an alternative. There's also Nvidia Shadow Play, if you don't mind their account login requirement.

H-V, do you run on Win11 Home? About the time I "upgraded" to Win11, the Desktop capture source subwindow doesn't show at all--only the built-in camera shows. I did try setting in NCP Auto-Selected, but still no Desktop to capture.

@Eugene-Beer I have win11 Pro on my laptop. I set it to Auto in NCP and can capture Desktop. I also follow the link above it in NCP which leads to Windows System/Display/Graphics and add vp20 setting that to High Performance (Nvidia GPU)... don't know if that part exists in Win11 Home.