Spherical panorama export after merging layers

i'd strongly recommend to avoid PS here at least partially. there are a lot of better tools out there for remapping a spherical panorama to editable cubefaces. you can (to name some options) do it online for free here (with size limits and JPEG only): https://nadirpatch.com, you can use (on windows only) the supercubic plugin: https://www.superrune.com/tools/supercubic.php, you can use the flexify plugin: http://www.flamingpear.com/flexify-2.html or use the professional pano2vr: https://ggnome.com/pano2vr . if you use ptgui (https://ptgui.com) for stitching, you can extract the bottom cubeface from a spherical pano, edit it in PS and re-insert it into the pano.
long story short: after the end of the PS 3D tools you can replace them by these tools delivering a better transformation/remapping quality while keeping the huge image editing power of PS including AIGF. - in my everyday work as a 360° pro the combination of pano2vr 7 with PS 2024 is a dream team as they together offer a nearly semi-automatic workflow.

Solved: I was using the merge option in the layers menu rather than the merge down command in the layers tab in the 3-D section. Moving around a 360 image is very slow in PS 2024 but apart from that, 360 panorama editing still seems to work.

Are you flattening the image after using 3D>Sperical Panorama>New Panorama Layer from Selected Layer(s)?

In order to Export the Panorama it still has to be 3D.

If you flatten the 3D pano then 3D>Sperical Panorama>Export Panorama will be greyed out regardless of the photoshop version used.

You can have both versions 2021 (ps ver 22.2) and photoshop 2024 (ps ver 25.1) installed at the same time.

You can't depend on any 3D functions to work right or at all in the photoshop versions past 22.2.

Thanks. I'm avoiding downgrading Photoshop as I'm using it particularly for the generative fill. The '3D-spherical panorama - export as' option works fine as long as I haven't merged any layers. I've also tried flattening the image but it also disallows the export. I'm trying to find a workaround within the current version of Photoshop.

I think your better off downloading Photoshop 22.2, the last photoshop version with fully working 3D to use any 3D related functionality.

You should be able to get Photoshop 22.2 using the Adobe Creative Desktop Application.

https://helpx.adobe.com/photoshop/kb/3d-faq.html