Thank you sir, really appreciate your help. Will read and digest.
Hello!
I'm having the very same problem in v0.20.6, running on raspbian stretch on a RP2.
I used the script to install
Please help 
In you web browser find the developer console and see if there are any errors in there
Hi!
Console shows me this:
Empty string passed to getElementById().
Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://catalogue.nodered.org/catalogue.json?_=1562102568900. (Reason: CORS request did not succeed)
Problem solved, Privacy Badger plugin was the problem!
thank you very much for the hint @ukmoose and for the fast response 
2 Likes
Welcome to the forum.
Since you are asking on an old thread of a member who has not been active here for 18 months it is likely that he/she will not see your question.
Looking at the solution, I assume he removed the Privacy Badger plugin.
If that doesn't help then please start a new thread and ask your question there.
