I noticed in your screenshot that you are saving the selection, not saving it as a path. Could you please share another screenshot? It appears that the option to save as a new channel is being offered, but the document choice is hidden.
I can't reproduce this issue. It may help if you could share a screen recording of your steps. Post a URL to the video using CC files or dropbox, YouTube or something similar to share the file.
Hi, this is still broken in both 24.1.0 and 25.4.0
In these three example PSDs, you can save selections between test_1 and test_2, but albedo_export_example cannot save selections with test_1 or test_2 and they cannot save a selection to albedo_export_example.
Full Repro Steps:
Open all 3 PSD files in PS 24.1.0 or 25.4.0
use lasso to draw a selection in test_1
click Select > Save Selection
In the Save Selection dialog, click Document dropdown.
Note that test_2 is an option, but albedo_export_example is NOT
repeat steps 2-4 in albedo_export_example. You will see no options except "New" in the Document dropdown.
Expected Result: All open documents are options in the documents dropdown of Save Selection.
Note: The only difference I can see between these is that albedo_export_example is not color managed (RGB/8#) but color management has nothing to do with raw pixel selection values so even if that is the case, its definitely still a bug and should be fixed.
Check the Color Mode of your document under Image>Mode.
For example, if the Color Mode is Bitmap, then you can only save a selection to a New Document if there are no other open documents that support alpha channels.