Recently installed Apollo with a swap partition and full LUKS system encryption and noticed the issue after the first boot.
Figured it out myself this morning on what was wrong and was coming on here to make a similar post and found yours. Question is, is this a problem with the OpenSwap package not creating a default config, or is this an issue with the OS installer?
Found this EOS Forum Post helpful as well when figuring out what was wrong.
Edit:
Seems this person was also experiencing the same issue, but never resolved their problem and the thread closed.