Providing a perfect entry point for users needing HW RAID protection with adequate capacity, the PROMISE Pegasus32 R4 series RAID storage system brings the power of Thunderbolt 3 technology to a wide range of Mac users. Apr 21, 2020 FYI, I am having the same set of problems since going to Catalina on my Mac Pro trashcan and Promise Utility v 4.04.0000.40 (C6) and P2 R8 firmware 5.04.0000.64. OS seems to hang on filesystem access to the array and never comes back until power-cycling the array. I am facing with the similar issue of not recognized Pegasus 2 R4 after a shut down through promise utility w ere you able to fix this problem. Since Promise technical team is asking me to get in touch with third party vendor even after my product is under warranty. Following is the reply from promise.
Providing a perfect entry point for users needing HW RAID protection with adequate capacity, the PROMISE Pegasus32 R4 series RAID storage system brings the power of Thunderbolt 3 technology to a wide range of Mac users. View the manual for the Promise Technology Pegasus2 R4 here, for free. This manual comes under the category Disk arrays and has been rated by 1 people with an average of a 8.4. This manual is available in the following languages: English. Do you have a question about the Promise Technology Pegasus2 R4 or do you need help? Ask your question here.
Symptoms: The Pegasus is showing no problems; WebPAM or Promise Utility gives all green checkmarks, Disk Utility will show 'Promise RAID' volume as mounted and it will pass verify disk, but Finder still doesn't see the volume. You might be able to browse to your external volume directly at the Terminal command prompt, or with the Finder option 'Go…', but the Pegasus RAID volume won't appear in Finder, on the Desktop, or within apps.
Cause: OS X uses the HFS+ filesystem, and to hide files from Finder it toggles the HFS+ hidden attribute on the files. Directories and volumes can also have the hidden flag set. Even while mounted correctly and having an clean filesystem, the folders or volumes will not show up in Finder. The hidden flag needs to be turned off within OS X. This problem has been reported with all types of storage, and is not unique to Promise hardware.
Solution:
How to Remove the Hidden Flag on the 'Promise RAID' Volume

- Open Applications folder.
- Open Utilities Folder.
- Open Terminal.app.
- At the $ prompt, type: sudo chflags nohidden /Volumes/Promise RAID/ and press Enter. (If you have renamed the Promise RAID drive icon, then please type its name, instead of Promise RAID, after Volumes/. Tab Completion is a powerful feature, just type Pro and hit the Tab key to have it fill in the rest.)
- Enter your password at the password: prompt.
- At the next $ prompt, type: sudo killall Finder and press Enter.
- All your Finder windows will close and reopen, and the Promise RAID volume icon should be visible again.