I founded bug.
Maximum number of rows skipped by condition
INTO TABLE rl246 WHEN (1)='8'
is 1264. When number of skipped rows is from 1265 to 1276 then sqlldr displays second error SQL*Loader-2026 with hint add SKIP=1278 (I had SKIP=1 and one not skipped row: 1+1+1276=1278).
I started with 90k rows and I had no idea where is problem.
Maybe is it bug 1721550 from year 2001 , 8.0.6.2.0 !!