This issue persists in v.20095. The Modal window appears blank or it doesn't appear at all.

Great.
Can you try changing the CEF_DIR path to point to C:\Program Files\Adobe\Acrobat DC\Acrobat\acrocef_2, and check if works for you?

Found it!

CEF_DIR : C:\Program Files\Adobe\Acrobat DC\Acrobat\acrocef_1

This folder exists and contains 12 items incl. folder "locales"

For Acrobat 64-bit, please check the following path -
HKEY_LOCAL_MACHINE\SOFTWARE\Adobe\Adobe Acrobat\DC\Installer for CEF_DIR path.

Does it have the same folder path as you shared below (C:\Program Files\Adobe\Acrobat DC\Acrobat\acrocef_2)?

I have no CEF_DIR key at:

HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Adobe\Adobe Acrobat\DC\Installer

but I can find the following folder:

C:\Program Files\Adobe\Acrobat DC\Acrobat\acrocef_2

Btw, I have "Acrobat DC 64-bit for Windows" installed.

Hello,
We are investigating the issue you have started facing with the latest Acrobat update. Would like some more information from you -

Could you please check what is the folder path shown in "CEF_DIR" key at the following registry -
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Adobe\Adobe Acrobat\DC\Installer?
and if that folder path actually exists on your machine?

To check the above registry, please go to Start->type "regedit" and press <ENTER> key. This will open registry editor.

To help identify if this is indeed the culprit, could you please try changing the value of "CEF_DIR" registry path to the folder that exists on your machine. Look for a folder path like "C:\Program Files\Adobe\Acrobat DC\Acrobat\acrocef_x" where x is the number that exists on your system. It will be something like acrocef_1 or acrocef_2. Please let us know if this fixes the issue.

Thanks for your patience,
-amboo

This problem does not happen with every PDF file. Since I'm frequently use redaction, I tested it with several PDFs and what happened was that when I tried to "apply redactions", the (modal) window "Apply Redactions" appeared without any content. I can get back with the ESC key but applying redactions (a single or across multiple pages), does not work for these files

Hello,

We apologize for the inconvenience caused. Could you please share more details on what is the exact issue you are facing with the latest update in redact workflows? It would be helpful if you can share a screenshot of the problem. Are you on Windows or Mac OS? Is this problem with all files or any specific file?

Thanks for your patience,
-amboo