Latency remains in session after removing Fab Filter L2, gets cleared opening Logic mastering tool

This is a 2019 Intel iMac. (See EtreCheck Report below.). After putting Fab Filter L2 on the mix bus, then completely uninstalling it, the latency stays with the project even after saving and reopening. If I open the Logic mastering tool, turn it on, turn it off, then completely remove it, the problem goes away.

It's as if the project doesn't get a "reset" after removing the latency inducing plugin.