Strange SSTO glitch/bug?

[A35K]

So I am playing carreer mode in 1.5.1 with the following mods:

-Interstellar Extended

-Kopernicus with OPM

-KAS

-KW Rocketry

I built an SSTO plane a few weeks ago, made of stock parts only  (mk2 fuselage with 2 whiplashes and 2 aerospikes). It worked great and I have used it multiple times, then today I went to launch it (in the same configuration, no additional payload) and it couldn't even break the sound barrier. I tried a few other previously successful SSTOs and the same thing: All except the smallest of spaceplanes get 'stuck' at about 300m/s. I relaunched KSP and they all worked again, but today I was playing and the same thing happened. Its annoying because I have to restart KSP multiple times to get rid of it. I am always following the same ascent profile and everything is the same. I have no idea what could be causing this, as I have definitely not updated KSP or any of my mods before this problem started. I know Interstellar adds certain mechanics to the stock jets but as I said these planes worked perfecty just yesterday. Any ideas or something similar happening to anyone?

 

[Xd the great]

Any chance you forgot to install dependencies?

Any antivirus stuff messing with ksp?

[A35K]

Thanks for the help, but it turns out it was my fault after all. I was editing some small things on the payload and in putting the cargo bay back, it attached to a node on the payload rather than the rest of the fuselage, but it looked normal unless you really zoomed in on the joint (which is why I only caught it by accident). Apparently that little uneven bump on the fuselage is enough to completely ruin my Mk2 SSTOs. The reason why it worked when I restarted was because it reverted back to the craft file with the proper cargo bay attachment.

Edited December 28, 2018 by A35K