Any suggestions here?  I'm going to dig into this now.  I'm not entirely sure what's happening at the Block level, but I think when I transpose to interpolate along axis 1, the arrays actually are floats.  I then reconstruct (with float blocks) and transpose back to the original shape.   I suppose I could try recasting as `int64` after I've transposed [here](https://github.com/pydata/pandas/pull/4915/files#diff-03b380f521c43cf003207b0711bac67fR2047)?