Business purchase - multiple licences added to the same account. Device limit breached after 2 devices connected. Why when multiple licences have been redeemed?

We have purchased over 40 laptops but have previously registered (Acrobat 2020) with a single account and assigned a device to each registration. 
We have now moved to Acrobat 2024 using the same process but on the 3rd device the device limit has been reached. Why?
It is not practical to assign registrations to individual staff members as they ‘come and go’ so we need a static account which has worked perfectly in the past.
Where are the missing licences and why can’t we assign them to the devices as before?