Update: Enscape just got back to me after reviewing a file I sent them and they did say it is an Enscape bug.
They advise that it would usually not occur but because you imported the materials instead of creating them in Sketchup; this is the result.
It’s fixable with an adjustment that the developers wanted to work on for 2.7.1, even though that’s more of a feature than a bug. So,it should be fixed in Enscape 2.7.1.
A workaround in the meantime is to check the “explicit transformation” checkbox for the albedo slot before you make any changes. The scaling should then be retained.