I've checked that all the files are present:
And have tried:
Install-SPHelpCollection -All
Install-SPHelpCollection -LiteralPath 'C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\HCCab\1033\MS.OSS.HC.CAB'
Install-SPHelpCollection -LiteralPath 'C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\HCCab\1033\MS.OSS.ADMIN.HC.CAB'
Get-SPHelpCollection returns no info. I've also checked the Central Admin /_admin/privacy.aspx Privacy Options to display external web-based help, and the Help Settings in Site Administration.
Please help! Any suggestions would be very much appreciated.