Thank you for your reply.
The log isn't showing any exceptions.
I made two new, more clear Screenshots for you, to reproduce the issue.
The first one shows the setup to reproduce:
You just need a lander pod, a 1.250m Interstellar Fuel Tank 48 (sorry, 1.875 was wrong, it's 1.250m) and two stability enhancers.
Once you release the stability enhancers. The construction won't fall down to the ground. It just rotates and flips around, just like it is fixed by something near it's center of mass:
Best regards