Because of the plurality of areas, it sounds a bit odd to my ears to say "Areas to investigate in the future could be data quality issues or system compatibility". To me, the "be" should rather be "include". Are both correct, and are both common/idiomatic use of English?
I tried searching for it, here and more broadly on the web, but "be" is very broadly used of course. The word coming after it could be anything so I can't do a literal "be [word]" query with quotes, and while the word before is more constrained, "could be" is very commonly used before a single item as well as in other settings, so I couldn't find an answer as to whether it can be used before a list.