Kerbal Space Program

Dear KSP team,

I have a weird issue I believe is a bug. I have checked it on internet and could not find any feature that would explain this issue

I am currently trying to land a rocket on Eve, aiming at later coming back. For this reason, I have a relatively small spaceship inside a 3.75m Airstream. This airstream is placed on top of a fuel container + engine.
Upon being slowed by Eve's atmosphere, my fuel container get destroyed by overheating, leaving nothing but the airstream and the spaceship inside it. At this point, the only element in contact with the atmosphere is the airstream. The problem is: from then on, my airstream is not slowed down by the atmosphere, and it actually orbits Eve, even though the periapsis is at 55km and the apoapsis at 88km.
To be exact, the periapsis and apoapsis do change, but they are stuck in a cycle: when the ship is at the periapsis, the periapsis lowers by a few meters, while the apoapsis raises by about as much. When the ship is at the apoapsis, the apoapsis lowers while the periapsis raises - all by a few meters only. The orbit seems to remain stable long-term.
If I open the airstream, then the ship is interacting normally - it gets slowed down by the atmosphere and gets destroyed by overheating pretty quickly
You will find attached my saves right before the entry getting my fuel tank to overheat and explode

Please let me know if you need further information, and of course, thanks for the awesome game
Benoît

PS: I play with no mod and in french