Issues running Beachhead maps in 3.28 Standard

The patch notes for 3.28 mentioned that Beachhead Maps could no longer be obtained, but I have not been able to run the ones I have from last league. There are Beachhead sections of the map tab, and my existing red Beachhead maps have become 'Beachhead (Tier 15)' items but I cannot use them in the map device. Is this intended?

I get that they can no longer be obtained but why can't we still run the ones we have?