I have spent some time on this and not sure why the admx and adml files from LAPS are showing up for me in local policy on a few different machines (when placed in C:\Windows\PolicyDefinitions), but the settings are not available when creating a new GPO. I copied the admx and adml files to the appropriate C:\windows\sysvol\domain\PolicyDefinitions folder on a domain controller (we are using a central repository).
I even deleted them and tried again. I see the files in the \\domain.local\SYSVOL\domain.local\PolicyDefinitions folder which is replicated amongst the domain controllers. Is it possible the current msi installer for LAPS has buggy admx/adml file?
Okay feeling very stupid. I had a policydefinitions folder at \\<domain name>\SYSVOL\<domain name> and also one at h \\<domain name>\SYSVOL\<domain name>\policies. Obviously the correct one is below \policies.