Trying to IVM Tag newly discovered assets with AD OU but regex fails

trying to pattern match this to get OU=Computers,OU=BLAH but I keep only getting OU=Computers.

“CN=blahblah,OU=Computers,OU=BLAH,DC=ecorp,DC=com,DC=org”,

regex:
OU={{ou:/(.?[^\])(?:\\)/}},

and multiple matches is ON

What about something simple like {{ou:/[a-zA-Z\s_-]{3,}/}}