What could be the cause for standard SharePoint help to override the Nintex help window? Any site customizations that could affect this?
Alexey, Just to be clear, this popup is the result of clicking the Help button from the ribbon of the action, or from the SharePoint help button in the top/right most area of the window?
Most likely the Nintex Workflow Help is not installed properly. Can you verify that in SharePoint Powershell Management Shell, by running Get-SPHelpCollection command. Can you see Nintex Workflow 2013 Help and How-to in the list?
If you can't see it in the list, can you try to run the command below to re-install the help file again?
Install-SPHelpCollection -LiteralPath ([Microsoft.SharePoint.Utilities.SPUtility]::GetGenericSetupPath("HCCab") + "\1033\Nintex.Workflow.HC.cab")
Please posted the error message if you get errors when running these PowerShell commands. Thanks
Even in NW2013 International build, we will still install HCCab. Probably ask your farm admins to check whether the Nintex.Workflow.HC.cab are exists in SharePoint hive?
If exists, then retry the Install-SPHelpCollection command to install the help in your farm. If still cannot see it after run, please check ULS logs to see whether any error messages.
Note: The help file (Nintex.Workflow.HC.cab) will placed in 1033 folder only, mean only English version supported.
I know you should have included even more HCCabs for every supported locale, but the files are not there on any of the servers in the farm neither under 14 nor under 15. We plan to install a newer release and this will be one of the smoke tests of success. If the files don't turn up, I'll submit a support case.