How critical is PCB layout for USB Full-Speed?
The PCB layout for USB Full-Speed is somewhat critical. It is more critical than the layout for a 400 kHz I2C bus, but not as critical as a 6 Gb/s SATA bus.

It is possible that you have layout issues that are preventing the downstream devices from enumerating. These "issues" might include, but not be limited to, proper layout of high speed signal paths. You might also have a problem with power distribution or bypassing. Maybe you installed the wrong resistor somewhere. Perhaps you have a bad solder joint on a connector.

You might want to try asking a more specific question and providing much more information if you need more detailed advice.