MOTU Audio System effects suddenly do not appear as Inserts in the Mixing Board. The Audio System is set to MOTU Audio System.

MOTU Audio System effects install into the System Folder: Extensions Folder: MOTU Folder: Plug-ins Folder. Verify that they are installed in this location.

If the effects are correctly installed, there may be more than one copy of MOTU Audio System on your drive. Run Find File and Search for "MOTU Audio System," and remove any copies that are not installed in the MOTU Folder in the Extensions Folder. Since MOTU Audio System is not an Extension, it does not necessarily need to be in the Extensions Folder to activate.