Hi @leadfoote
Thank you for your question.
The ODVA EtherNet/IP (Explicit messaging) driver does not support indexing in macros. Our recommendation is to use the Modbus TCP/IP driver you have set up, as it is better suited for indexing as you mentioned. If needed, here is also a forum post demonstrating how to index in macros: LINK
For the Modbus value flipping to zero, could you send a screenshot of your configuration? Please also ensure that all data types are consistent between EasyBuilder Pro and the connected device.