PR55-34 Radio has problem with 6-Digit Modbus-RTY addresses

We are using the PR55-34 as a complimentary Modbus-RTU wireless link to our systems, and these work flawlessly using Modbus-RTU 5 digit registers. Unfortunately, these radios seem to not like Modbus-RTU 6-digit addresses. The response from slave devices is random and 99% of the requests are not processed and we see comm timeouts. Does the PR55-34 radio module have a work around to allow using 6-Digit Modbus-RTU addressing?