I'm running RNA extracted from Saccharomyces cerevisiae in a Tapestation 4200. The RINe value is excellent, but the sizes of the 18S/28S bands are lower than expected: ~1000 and ~1800 instead of ~2000 and ~4000, respectively. The internal control (lower marker, 25nt) in each sample ran as expected. Yeast don't seem to have a hidden break in the rRNA.
Has anyone experienced a similar problem?