Answer
On Apps9 specifically, this was addressed by a dedicated patch (delivered with a later Apps9 Update); apply that patch and reconfigure the application server, which regenerates a new setup ZIP package, and reinstall Crystal Web Service from that newly generated ZIP rather than the original installer package. The underlying fix is included natively in Apps10's core install package, so this specific virtual-directory installation issue is an Apps9-track problem requiring that patch-plus-reconfigure-plus-reinstall sequence.