-e -l <N> would never pick order = N. At most order = N-1. Or do I misinterpret the flac -a output? (I read the "order=" part, which does not start at 0. order=7 means coefficients enumerated 0 through 6, and was the highest I got out of -l7.)
Anyway, a bunch of .ana files attached.
Also, with -b48000 - so the blocks "nearly repeat", but not exactly - the predictor coefficients do vary quite a lot between the frames. However as a sine should be perfectly replicable with order = 2 - presuming sufficient precision, which I am too lazy to check out - there would be a whole lot of different predictor vectors that would make for equally good prediction.