It has to do with poor QA from Carenado. It seems they never tested having all three planes installed on the same installation and what the interactions were between them.
Again, the reason Jay did this was because, well, it starts with the way MSFS works. It reads in files in the order of the packages listed in content.xml. Sometimes, it’s smart enough to know particular files are owned by particular packages and it keeps them in memory even though another package has a file with the same name, sometimes it doesn’t know that, and just overwrites the data it’s keeping from the last file it read of the same name. I don’t know why, but, to me, is indicative of rather sloppy programming on Asobo’s part. Same thing with what Martial said about most CTD’s have to do with “uninitialized memory”… Really??? These are supposed to be professional shops.
In this case, no matter which plane you’ve chosen to fly, it reads in Instruments.xml of say the Mooney, then, it reads in the instruments.xml of the Seminole, and promptly forgets all the data from the Mooney Instruments.xml file, then it reads in the Instruments.xml of the YMF, and promptly forgets everything it read in before.
Therefore, by adding in the extra templates from the Mooney and Seminole, now MSFS has all the templates it needs for whichever plane you choose to fly.
I’m not sure who has to fix this, Carenado giving each Instruments.xml file a unique name, or, maybe they are dependent on Asobo to fix this problem. Or, maybe it has to do with the way Carenado is naming their instruments. I’m not familiar with gauge design to that level of detail.