Undocking a vessel attached with struts causes it to not undock and/or split in half

[FailSpace]

Windows 10 Home 64-bit

English

System Manufacturer: Micro-Star International Co., Ltd.

System Model: MS-7B48

BIOS: 2.30

Processor: Intel(R) Core(TM) i3-8100 CPU @ 3.60GHz (4 CPUs), ~3.6GHz

Memory: 8192MB RAM

Page file: 17741MB used, 6282MB available

DirectX 12

 

Severity: Med

Frequency: High

I was making a rocket to go to Eeloo. I had made the mothership with(from top to bottom) a cupola, that four-seater capsule, a large reaction wheel, six large cargo doors(inside was a lander with a tuna can capsule, medium fuel tank, RCS, landing legs, and a dart engine. it was connected to the RTG using struts), a large RTG, a ball hydrogen tank, solar panels on the sides, and a SWERV engine. I don’t remember the rest of the vehicle. I’m in Eeloo orbit and I just undocked, and it caused the ship to split it half between the RTG and the cargo doors. 

[FailSpace]