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I noticed that recent item lists were also blank in non-Adobe applications, such as Excel and Word. This led me to believe that a system-wide setting was changed. I downloaded and installed Avira Privacy Pal, and it turned out that I was correct. In Privacy Pal there is this setting: User Privacy > User Activity > Don't keep history of recently used documents (for anyone else reading this thread, you need to be in "expert mode" in Avira to access this setting).
After I deactivated the setting mentioned above, Acrobat returned to its normal behavior of keeping track of recently opened documents.
I consider this issue to be solved. Thank you!
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Anand,
Thank you for the instructions. I followed each step until I finally reinstalled Acrobat Pro DC 2018.011.20035 using the Creative Cloud app. Please note that this version seems to be older than the one I had previously.
Unfortunately, the recent files list remains unpopulated. I attempted to open multiple PDFs, but the list remains empty. Are there any other steps I can take?