>>1) That the data structure changes actually happened. He sent me the two relevant tables after running the update code the other day and the new memo field is there; the old char fields are gone. Since he could find these where expected, I think I can also rule out something related to virtualization.
>
>Looks like I was wrong and maybe this is a virtualization problem. I got remote access to their system and am testing bit by bit.
>
>I've confirmed that the app is looking at the folder I expected for data, and that the table is the one I think it is. However, when I test for the memo field's existence, it's not there. Specifically, I added this code to the main program:
>
>

>WAIT WINDOW "Data folder is " + m.g_data
>USE ProdList
>WAIT WINDOW DBF("ProdList")
>WAIT WINDOW "ProdList " + IIF(TYPE("ProdList.mNotes") = "M", "has ", "does not have ") + "memo field."
>USE 
>

>
>g_data is a variable that holds the path to the data (retrieved from another table). It's the folder I'm looking in, and DBF("ProdList") is the file I'm looking at. I can see that there's an FPT (which wasn't there before I ran the update code), but the test above says it doesn't have the memo field. I copied ProdList.* to my machine and I can see the memo field is there.
>
>So despite all evidence to the contrary, it appears to me that the application is not using the file I think it is. Here's the set-up.
>
>Client machine is Win10 (but the app gave the same bug on a Win7 client earlier).
>Server is Win7
>The data is on a mapped drive and is not in the Program Files hierarchy.
>To test, they've turned off virus scanner on both machines.
>
>Is there a way to actually check whether a file is being virtualized? Also, why wouldn't the updated table be properly virtualized regardless?

While your app is running on the client computer, you can go to the server computer and go into Computer Management. You can then go into Shared Folders...Open Files and that will show you the files actually in use.