Do you have AEP Assurance installed on your app? Can you look at what data is actually being sent to Adobe...
There should be no data manipulation on Adobe's side (unless for some reason you have a VISTA rule set up to do this.. which seems unlikely).
You cannot force a case with Processing Rules either (unless it's specifically if value is "x" send "X")...
So there are 4 possibilities:
1. The data being sent to Adobe is in Titlecase (you need to test this)
2. There is a very specific Processing Rule changing "walmart" to "Walmart"
3. There is a VISTA rule manipulating the data
4. This one is a bit odd, but Adobe used to be fully case sensitive so "walmart" and "Walmart" would appear in separate rows... now they take the first version recorded (probably in the month.. but maybe longer) and apply all variants to that first version... so if you made a change in your app recently, or maybe you have web and other sources in your suite that had "Walmart", the data you are sending may be rolled up under the wrong variation....
