How to rescale a grid in FoundryVTT and keep the doors/walls?

I’ve discovered an issue when importing maps from dndbeyond into FoundryVTT via the VTTAssets Dndbeyond extension.

The map imports 100% correctly in that it brings in walls and doors as well as keeps the scale of 1 square = 10 feet.

However, I want to play with 1 square=5 feet, but keep the same dimensions.

If I double the map size, the doors and walls don’t double with it. It does put 2 grid squares in each map square, but I was hoping to keep everything when the scale changed.