Office 365 –Missing Nintex Icons on the top ribbon

While working with Nintex in office 365 environment, suddenly Nintex forms and workflow icons are missing as shown the image below.

I have all the site contents, I am seeing Forms and Nintex are installed as shown below. 

I have verified all the details and permissions ( I am site collection admin). I have verified the post from Nintex community but It wasn’t worked for me.

After verifying some time I had no clue on what next. Finally I found the post from swetha s to fix the issue. I have Removed and add re-add the forms app to the site as below.

After re-installing the app, I am able to see the forms icon on the top. But we have to design the forms once again and re-publish the forms and workflows (if you have task forms customized using Nintex forms) to the site.

Good. But next question in your mind – Do I need to add the app for all the sites in the site collect?No, don’t worry, it is just for one site and no need to add all the sites. 

SharePoint list Nintex form error – “The app Nintex Forms for Office 365 is out of date. Please update the app.”

While working with Nintex form in office 365 site I got an error saying that “The app Nintex Forms for Office 365 is out of date. Please update the app.” as shown the image below.

As I am new to Nintex forms, thought this is update news from Nintex team and tried to verify the option to update the Nintex forms by clicking on the Nintex forms in site contents. But I am unable find any update link on the app.

Going through few blog posts, I got the reason for the error. We got the error because of the script in the form. I wrote alet(‘hi’) instead alert(‘hi’). Silly right? Yes sometimes happens.

After fixing the error I am able to open the form without errors.