Having issues with behavior control - Web Group Filtering

are there any tips to get this to work?

would really like to have a short list of white listed web site for use by the younger ones in my family
this would be great, much better than maintaining a list of blocked websites and a NSFW list

documentation referenced

created an IP Group using MAC IDs

URL Filtering doesnt work for me - kept getting PR_CONNECT_RESET_ERROR for what was a whitelisted website
tried a number of variations, then gave up, seemed pretty flaky

Then tried Web Group Filtering, had a little success, but some things are not working.

Set up a web group for Whitelist with one entry
 for testing, got that to work
(note, the router did not like  was okay)

Under web group filtering, set up policy for Allow and Block

Allow is ID No. 1

Block is ID No. 2 and uses the system provided "All" for Web group

going to one of the managed devices, most websites timed out, which is fine for a blocked site

But, was able to get onto you tube, not good
Looks like changes are immediate, just save the entry in the router, no re-booting required, kindly confirm the behavior
note, browser caches were cleared before testing on the managed device

But I cannot seem to get Lightgliders (one example) to work on one of the managed devices

TP Link wont accept this URL
Also, it won't take wildcards like the URL filtering
works in the tool
but on a managed device, I get a message stating:

Since some entries work and some do not, is there another website that needs to be whitelisted?

are there any tips or tricks to make this work?