It seems as though the % sign is required. Checking the source code for PLC4x, the regex for eip tags is as follows:
or according to the documentation:
Unfortunately Rockwell addresses don't fit this scheme and are rejected.
I found it odd that they don't end their regex with a $, which means that something like %I:0/0 is a partial match, but nonetheless throws an exception
org.apache.plc4x.java.api.exceptions.PlcInvalidFieldException: Invalid field %I:0/0 invalid
Stripping off the /0 (as in %Q:0) isn't rejected by PLC4x but instead OpenPLC rejects it as unsupported.