Strange happenings in X-Plane

I recently tried a new aircraft, which several users had praised its flight model. Guess if I was surprised when I found out that nose down trim didn't suffice to keep it level at 80kt+! Needed lots of forward yoke pressure even if I moved the CG forward unreasonably far.

The pilot viewpoint made me feel too tall, so I moved it down in Plane-Maker -- and now trim range was working quite well (I had considered extending it when already in Plane-Maker). Hmm... maybe saving it in 9.67 did something version-wise? Nope: Re-installed the original and it worked fine too.

Only reason I can think of is that an aircraft I flew just before it "did something" with its plugin(s).

Not the only strange thing I've found when it comes to flight model and flying an aircraft after another, but the previous time it was an aircraft which had only one rudder section. Don't remember exactly how the bug manifested, but it had to do with if you started X-Plane with this aircraft or if you had an other loaded before, so the bug wasn't easy to replicate as it took several specific steps to make it appear. To other people it either seemed like it was random or didn't happen at all.

But I've worked as a professional bug finder. On the development team I was the only one who could always crash a system and every time tell the coders what to do to make it crash again. So when we had a final week of acceptance testing at another location, the other nine were given tasks they were to concentrate on, but I got a free hand to do "anything at all".

And last, a screenshot showing which aircraft I've got in my active folder today: