I tried to connect a vector of three elements to axi_intc. After exporting to SDK and running libgen, I got the following error:
ERROR:EDK - intc () - Internal error: Num intr inputs 3 not the same as length of xget_interrupt_sources 1
ERROR:EDK:3416 - Error(s) while running TCL procedure generate().
The workaround is to separate the vector into individual signals and then connect them individually to axi_intc.
Example for external interrupts: