USB Repeters are not generally know for their reliability, but since we're talking five meters, it cannot be avoided.
You may try adding in a single USB PCI Card, and move one or two of the cameras there. See if they become more stable.
In order to really troubleshoot such an unusual configuration, you would need to monitor voltages, and look at noise around the installation. Probably not very practical. Basler ACE and others like them are very small cameras that excel at these kind of applications. USB is really not the way to go.
