Here's one of those rare situations where a screenshot is the best diagnostic. And I actually do think it's the EDS files !
Here's why: RSLinx Classic can "show" a device pretty well if it knows its Identity, which it gets as a response to the browse function. The device Type will allow it to show a general icon, and the device Product Name will allow it to show that module's part number.
Typically you'll see a generic icon, and the words "1756 Module" and then the part number, like "1756-ENBT/A".
But the Identity object does not include the kind of bridging and routing information that's in an EDS file.
It is very common to "see" a 1756-ENBT or -CNB on a network, but to not get the characteristic "+" box to the left that indicates that RSLinx can "drill down" to the next level.
With CompactLogix there's another wrinkle because the "virtual backplane object" that allows the CompactLogix to present its internal buses as CIP buses like the 1756 ControlLogix has an EDS file of its own. You could register the EDS files for the 1768-ENBT, for example, as well as for the 1769-L43, but if you don't also register the EDS for the backplane, you won't be able to "drill down".
You could install a current copy of RSLinx 2.54 to get all the EDS files included in it, but depending on how long it's been since you updated the rest of your software you might run into some dependency issues (I did, with RSNetworx v7).
Instead, I'd download the EDS files, maybe more than you need, and use the RSLinx EDS Registration Tool to install and register them.
