Missing pages from 1950 census in Gilchrist County, Florida

I was looking at the 1950 census for this county, and I noticed several districts (21-2, 21-3, and 21-4) had a single page that says "Frames for this Enumeration District (ED) were not on the original microfilm reel as indicated by the Census Bureau."

Does this mean the records from these EDs are lost to time forever? Is there a master list of which districts nationwide are affected?