Automatically Link Users by Email Not Working

No worries. We'll be releasing v5.1.2 soon (if we can test and fix that last few things we're working on). If you do find something critical, we'll gladly help get it going and release a v5.1.3 if necessary.. though we're hoping 5.1.2 will be the last v5.1 release.

Again though, no one else has reported this and the auto-linking of users is a very common/popular feature. Doesn't mean there isn't a bug, but it's likely specific to your configuration in some way, if so.

Thanks,
Alex