Too late for this maybe, I bumped into this issue recently but I figured out why and solved it successfully. At first, sudo perf list only gives me few lines of events
For those who need the complete hardware events in perf and is not shown in perf-list, you need to install the latest linux-tools.
sudo apt-get install linux-tools-4.15.0-106-generic linux-cloud-tools-4.15.0-106-generic linux-tools-generic linux-cloud-tools-generic
sudo perf list > perflist.txt
Now I get 1980 lines in perflist.txt