Nintex 2016 workflow designer ribbon is disabled and form designer does not open
After successfully installing Nintex 2016 (Workflow and Form), the following error may occur:
Nintex workflow designer ribbon is disabled or grey out.
NIntex form designer does not open after choosing the form type (Responsive or Classic).
Go to the server where the Nintex was installed.
Navigate to C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\TEMPLATE\LAYOUTS
Find the folders named 'NintexForms' and 'NINTEXWORKLFOW'.
Copy these 2 folders
On the same folder under C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\TEMPLATE\LAYOUTS, find the folder with SharePoint Build Number (i.e : 16.0.4561.1000). You will find 2 build number folders due to the SharePoint Server 2016 side-by-side functionality has been enabled in the SharePoint environment.
Open this SharePoint Build Number folders and paste the 2 folders that has been copied in step 4. Repeat this steps on both build number folders.
Repeat all the steps above to all servers that has been licensed as Web Front End servers in the Nintex License.
This issue happened because the farm has SharePoint Server 2016 side-by-side functionality enabled. When there is 2 build number folder exists, Nintex unable to copy some files under both folders, therefore the copy process need to be done manually.