Hi,
the BGL contains normally more then one airport. So to delete an BGL is not a good way because you lost other airports also. The answer from your devs are very easy and simple wrong. It´s not an issue with the navdata files, it´s an issue with the priorities in the sim scenery file.
Therefore, please follow these steps and you will see, all is good after that:
Thank you very much,
Richard
PS: by the way - I have installed the “Azurpoly LFTH” scenery