How to get build 15.1.2308.14

I installed CU 21 for Exchange 2016 and then installed KB5004779 (as admin). The health checker is showing my build as 15.1.2308.8 with the KB5004779 installed. Per the build docs I should be at 15.1.2308.14 instead of 15.1.2308.8.

Do I need to do something else to get to build 15.1.2308.14 ?