Validated AU plugin does not appear in Mixer
I am configuring a new 2018 Mac mini to replace my studio's 2010 Mac Pro. I've successfully installed almost everything, but I'm having trouble with one AU plugin. In the Logic Pro X Plug-in Manager, the manufacturer's name appears in the manufacturers area and if I click on it, the plugin appears as validated in the plugin list. "Use" is checked. Yet when I try to add the effect to a track in the Mixer, neither the manufacturer's name nor the plugin name is in the pop-up list of effects. The plugin works fine in Reaper, but I can't seem to insert it in a track in Logic Pro X 10.4.5. Reset and rescan does not fix it, nor does quitting and relaunching or restarting the computer. The plugin license is valid and on my iLok.
Any ideas?
Ralph Jones
Mac mini, macOS 10.14