Beginning of this year I reported about some problems I encountered with repeat controls getting data from @DbLookup and @DbColumn. Specifically if the returned results were a single value. These are not returned as arrays.
The other week I encountered a similar thing while displaying a multivalue field through a repeat control. Here is the catch: although the field is declared multivalue on the Notes form, when accessing in Xpages a multivalue field containing a single value is not passed as an array. So you will have to catch it and convert to an array for use in a repeat control.
Also see:
Xpages and the failing repeat control
Getting unique results from xpages @dblookup and @dbcolumn
