When using the sqlite backend, right clicking on a transaction that already has an associated file/location does not allow us to open the associated file/location.

Easily reproducible:
1. You must be using sqlite backend.
2. Right click a transaction, associate with a file/location.
3. After associating, you can verify that it is associated by opening it (right clicking again, open it).
4. Quit gnucash (might work to just open another gnucash file then come back).
5. Open the sqlite file again in gnucash.
6. Go back to the transaction where you made the association.  The "open file/location" option is grayed out.

When I examined the sqlite database, it looks like the association record *does* show up in the slots table, so it seems like it is saving the association, but not loading it properly when first opening up the file.