When selecting a guarantor for a child, there are certain conditions that prevent you from selecting a guarantor:
A) Guarantor has apostrophe in city: If you search for a guarantor by name or card number, and the guarantor's city has an apostrophe, you can't select that guarantor.
B) Guarantor has apostrophe in library name: If you search for a guarantor by name, and the guarantor has an apostrophe in the library name, you can't select that guarantor, but if you search for that same guarantor by card number, you can select it.
I think Bug 16450 will fix this bug, but I'm not sure if it's easy to pick for 3.22.x.
(In reply to Owen Leonard from comment #1)
> I think Bug 16450 will fix this bug, but I'm not sure if it's easy to pick
> for 3.22.x.
Confirmed, it's fixed in master.
*** This bug has been marked as a duplicate of bug 16450 ***