Apron and Taxiways materials issue

Since the latest MSFS 2020 major update (XI Canada) and SDK 0.19.3, there have
been major issues with changing materials for Aprons and Taxiways. Whenever,
the default material is changed, no new material is displayed but a chequered
texture (see enclosed image). A red error message can be read from the
Material Inspector : “Material is not from selected assets group and can’t
be changed. Save, Delete, Reset and Apply locked”
The new Nvidia driver
update (517.48) didn’t solve anything.

Thank you for your assistance

I found a way to get the Materials Editor to work. While with previous versions I was used to using the Apply button, after choosing the material, now you have to use the "drag and drop" technique; taking the name of the material and moving it to the appropriate object properties box works fine.