Caching is an incredibly important part of site performance, so it is not to be taken lightly. But sometimes (especially when you don't have a dedicated IT person with a organization-specific strategy) caching just causes things to not work as expected. We just experienced a frustrating issue with unexpected behavior when adding groups to subsites in a PM Roll Stack deployed for one of our Agencies. The Buddy Multi Network plugin was installed correctly and matching the exact configuration of our baseline servers. Long story short (though you can read the long story here - Brajesh is fantastic), we came to find out it was server-level caching that hadn't been turned off (in our case the server had a made a few migrations and the wp-config files didn't reflect the line that disables Spinup Redis caching), and the cache was actively displaying information according to the last ID updated (even though they were across subsites - obviously our Redis installation didn't know how to interpret). So, moral of the story is if you are experiencing weird behavior and issues, always make sure you are aware of and turning off ALL of your caching (Varnish, hosting-specific, etc.) when troubleshooting. It can save you a long winded headache.