Here's an update from Adobe on the bug:
The Lightroom team is actively investigating and working on fixing this intermittent issue of UI panels becoming Black, and we are close to finding a solution for it, however, it is not yet in the most current update (6.9/CC2015.9). We are hoping to have it fixed in next update.
For workaround information please see this document: https://helpx.adobe.com/lightroom/kb/lightroom-panels-black-issue.html
Thank you for your patience.
If you add your me-too vote to the bug report in the official Adobe feedback forum and follow that topic, you'll get notified whenever the status changes. (This forum is primarily a user-to-user forum.)
After you have opened the HDR image in Photoshop you can go to the Image->Mode menu option and choose 32-bit. However, you will discover that you have a very limited choice of tools to use in that mode. It's probably best to do as much of your editing in Camera Raw before opening the image in Photoshop..
Hmm, the forum software posted my reply in the wrong thread!
I compose HDR DNGs using Lightroom CCs built-in HDR merger with a typical dynamic range of ~22 f/stops.
How can I edit/export the HDR in 32-Bit in Photoshop? All options I found would reduce the bit depth to 16 bits/component. Even when I open the 32-Bit half float HDR DNG created by Lightroom in Adobe Camera RAW i cannot find a way to move forward with 32 bits/component. Is there any workaround for this?
This not an issue as explained at these two posts:
If I switch in Photoshop from 16-Bit to 32-Bit the HDR details are already lost from the 16-Bit import process and I cannot recover them just switching to a different mode.
I understood that the DNG half float format is used to store the HDR data in a compressed form which still delivers ~30 f/stops but less color precision. But when I do edit/export process asked in the original thread, it uses true 16-Bit (not 32-Bit half float), which means 16 f/stops.
Anyone has an idea how to get the full ~30 f/stops into Photoshop?
The DNG 16 bit Float format file can only be edited in LR or ACR with no capability to export as a 32 bit HDR file. If you need to edit the file in PS you have two options:
1) Apply your LR Develop module edits to the HDR DNG file and then use Edit in PS to open it as a 16 bit TIFF in PS.
2) Use LR Edit In> Merge to HDR PRO in Photoshop to create a 32 bit HDR TIFF.
What type of editing are do you need to apply to the LR HDR DNG file in PS?