I've got LR 11.3.1 release. It showed me couple of times for several weeks that there is a LR update, but there is no info in Creative Cloud / Updates. What is going on?
In the Adobe Creative Cloud application, top left, Apps menu, click on Updates.
If that doesn't help, sign out and then sign back in.
I doesn't help.
What version of macOS is your Mac running?
Because one possible reason for updates not being available for installation is if the computer does not meet the system requirements for the new version, and system requirements move forward over time.