Same comment as yesterday: What a horribly complicated circuit just to get a 50KHz sine wave.
The problem is the size of your coupling caps. Remove C4 and C5 (not needed). Make C6 about 10n. The time constant of the inter-stage coupling is ~1sec, so you would have to simulate for several seconds for the output to settle to its steady state (no DC component).
You could get a better low pass filter in one op amp stage than this. You could also get a low-distortion 50kHz sine wave directly, with no filtering required.
Learn how to post a real simulatable .asc file.