We ran into this issue as well and were able to resolve it with:

sudo find /Users/Shared/AvidMediaComposer/Search -exec chmod a+rw {} \;

We ran it once after opening MediaComposer and launching it as an admin and running scriptsync.  This fixed the issue for nonadmins that logged in afterwords.

This does open up permissions.

When we launched Avid we got a

"AvNN Error: 4618, Indexing database is not running. PhraseFind and ScriptSync are unavailable."

message in the console.

Trying to use scriptsync would throw the failed to get segment count from database error.