When you add a domain in whitelist through Web UI, the website is still blocked.
Solution 1 - Use command line:
Remove the domain from Web UI and add it by using pihole command line
pi@raspberrypi:~ $ pihole -w weeta.net
[i] Adding weeta.net to whitelist...
[i] weeta.net does not exist in blacklist, no need to remove!
[i] weeta.net does not exist in wildcard blacklist, no need to remove!
[i] Using cached Event Horizon list...
[i] 121,709 unique domains trapped in the Event Horizon
[i] Number of whitelisted domains: 8
[i] Number of blacklisted domains: 7
[i] Number of wildcard blocked domains: 2
[✓] Parsing domains into hosts format
[✓] Cleaning up stray matter
[✓] Force-reloading DNS service
[✓] DNS service is running
[✓] Pi-hole blocking is Enabled
Solution 2 - Move to dev branch:
The problem has been resolved in development branch.
pi@raspberrypi:~ $ pihole checkout dev
Please note that changing branches severely alters your Pi-hole subsystems
Features that work on the master branch, may not on a development branch
This feature is NOT supported unless a Pi-hole developer explicitly asks!
Have you read and understood this? [y/N] y
[i] Shortcut "dev" detected - checking out development / devel branches...
[i] Pi-hole Core
[✓] Switching to branch: 'development' from 'refs/heads/master'
[i] The install log is located at: /etc/pihole/install.log
Add the domain in whitelist through Web UI.