You haven't seen an error or a problem, you have seen a GSX feature.
What the FSX ATC calls "Gate 22", because the ATC is bounded by the FSX naming limitations, is in fact a Cargo gate and, since PHLI is a fully customized GSX airport, is properly named as "CARGO" (so you WILL find it under the "CARGO" group in GSX), as a GSX custom group name so, GSX is absolutely correct in this case.
The ATC assigned a Piper to the "Gate" 22, because it was flagged as "Ramp GA" in the PHLI AFCAD, in order to get rid of the default FSX ground vehicles.
We should probably have used a more descriptive name in the GSX custom name menu for PHLI, as in JFK for example, were something is listed both in the real-world correct name (made possible by GSX) or in the AFCAD name (constrained by FSX naming limitations).