Custom Usergroups & Member Search

[ANGLICO]

A subset of my forum members belong to a particular military association. I set up a forum for them, restricting access to those who are paid-up members of the association.

To accomplish this, I created two custom Usergroups. One for Association Members and one for Association Officers. The Sub-Forums I created for them are all accessible to the Association Members but the "Officers Club" Sub-Forum is accessible only to the Association Officers. All this is working fine, when I set the Primary Usergroup to the appropriate type.

HOWEVER, the Members Search tool will not locate these guys now. I run v 3.7.4.
I did remember to check "Registered User" under the secondary Usergroups. I'm reluctant to move up to a more current version, as there doesn't seem to be an automated way to save all the hundreds of custom settings.

Did I go about this all wrong? I'm trying to avoid the use of passwords by simply defining which Usergroup(s) can have access to this one forum area.

Thanks