RSD Silvertongue brew isn't giving a second roll on social checks.
As far as I thought the second rolls were applied in the script as taking the higher of two rolls...
Normally these social checks are script-specific though, scripts run during conversation dialogue to run these checks.
Are you able to list the NPCs that you think/noticed the second rolls weren't applying to so its easier for the DMs that manage the scripts to look into? Also the conversation dialogue lines would help them too.
Edit: and include character name*
If you failed it will immediately reroll and try again for persuade and bluff. It is working, you just do not get a message about it.
Which you now should get a message about.