Need to have some questions answered before we can support this:
1. Do they see any columns? E.g. bin, item, qty, and they are just missing some pieces of information?
2. Is it a grey grid where information is simply not displayed whatsoever?
If 1. they can configure the columns by tapping and holding the column header and selecting “Choose Columns”
If 2. Hard to say, perhaps their scanner version’s first 2 digits (e.g. v2.7) doesn’t match the extension version (e.g. v2.8). Perhaps they are on matching versions and need to “clear the profile”
Try clearing your cache under ‘Data’ in the configuration menu. If the problem persists, try clearing your profile as well. Once cleared, you will have to re-orient your columns (column visibility, order, etc.), so use this as a secondary resort.