DCS 2.0 import problems with channels

Product: Adobe Photoshop
Affected Version: 27.10
Last Known Working Version: 27.9.1
Platform: Windows

Description:
Photoshop 27.10 appears to have introduced a regression in the way DCS files containing multiple spot-color plates are interpreted.

The exact same DCS file opens correctly in Photoshop 27.9.1. In 27.10, the first custom plate is instead interpreted as Photoshop’s native Gray channel. After this happens, the spot-color metadata/tagging associated with the subsequent channels is also incorrect.

This affects production files used for screen-printing color separations, where every DCS plate needs to retain its correct plate name and spot-color assignment.

Steps to Reproduce:

1. Open the attached DCS separation file in Photoshop 27.9.1.
2. Open the Channels panel.
3. Confirm that the first plate and all subsequent spot channels are interpreted correctly.
4. Close the file.
5. Open the exact same DCS file in Photoshop 27.10.
6. Open the Channels panel.
7. Observe that the first custom plate is now interpreted as Gray.
8. Observe that the spot-color assignments/tagging of the subsequent channels are no longer interpreted correctly.

Actual Result in Photoshop 27.10:

The channel structure begins with:

• Gray
• #1 - Base White
• #2 - 3945 C
• #3 - Bright Red C
• #4 - 2728 C
• #5 - 446 C
• #6 - Highlight

The first plate should not be converted or interpreted as Photoshop's native Gray channel.

Expected Result:

Photoshop 27.10 should read the DCS plate names and spot-color metadata exactly as Photoshop 27.9.1 does.

The first custom plate should retain its DCS plate identity/name, such as Shirt Plate, and the following channels should retain their correct spot-color assignments.

Regression:

Yes.

The same file behaves correctly in:

Photoshop 27.9.1

and incorrectly in:

Photoshop 27.10

No changes are made to the DCS file between tests.

Impact:

This breaks DCS-based screen-printing separation workflows because Photoshop no longer preserves the intended relationship between plate names, channel data, and spot-color assignments.

Downgrading to Photoshop 27.9.1 immediately restores the expected behavior.

Additional Information:

I can provide:

• The original DCS file
• Screenshot of the correct Channels panel in Photoshop 27.9.1
• Screenshot of the incorrect Channels panel in Photoshop 27.10

This appears to be a regression specifically related to DCS/EPS plate parsing or the handling of the first plate in a multichannel DCS file.