The same images work fine in the develop histogram
Same here only this was also a problem for me in v. 7.2. I have Nikon NEF and Sony ARW. Same issue on both image types. If i go into Develop and do anything and then go back to Library the histogram shows up. But it is still missing on all the other imported photos. Shutting down and reopening did not fix the problem. I even reset my preferences which also did nothing for the problem.