Hey Alexandr,
Good question here that does show a website behavior difference. As a Partner, you'll see all SW available from Extreme in your Extreme Portal view. Access rules sill apply based on service level (entitlement = maintenance contract + product warranty), but it was important as a Partner that you'd see the file you were looking for, not just what you had access to (i.e. previous eSupport behavior).
(NOTE Customers have the same option, they just have to toggle to "see avail").
Make sense?
Also, the previous attempts to download EXOS SW for assets that prompted a case could have had a data alignment preventing the download. If you have a PartnerWorks relationship with any of these customers, you should be able to download code on their behalf. Clearly we need to investigate for you so this is more efficient.