Moisture is the most likely culprit. Sounds like you had a less-than-equalized piece to work with. That makes it more vulnerable to heat produced by scraping or sanding with pressure, as you encourage that bound moisture to come out fast. The checks that you started will be visible on the end grain, radial checks that were already started and encouraged to grow will run along the grain.
Scraping will always pick up fiber - nature of the beast. You can minimize the depth of torn fiber by scraping lightly with properly presented edges. Much better to practice those cuts which will cut across the fiber rather than into it. Take your pocket knife and a piece of wood. If you try to whittle by pushing the knife straight ahead you plunge, rip and raise fiber - a "catch." You can scrape with it held almost perpendicular to the surface, and it won't be too bad, so long as you don't press a lot, just as with scraping in a turning. Pressure will compress, break and tear, in addition to heating.
Now take that knife and draw it sideways as you shave, rather than just pushing it. The skewed angle and the modest sawing you do makes a smooth cut easy.
Translate that knowledge to your lathe tools, remembering that the piece is in motion already. All you have to do is choose the tool and presentation which allows you to control depth of cut - support by the bevel, and maintain a bit of skew, keeping the cutting edge as you did with the knife, where the deepest point of cut is the last point of contact - firm support of the rest.
You'll know you're there when your shavings are continuous, which makes them twist, and have a clean edge.
