This one drove me nuts for a while. Once I found it, it was very obvious:
oxwall-1.5.1\ow_core\form_element.php
Line 2639 (In class YearRange)
The setMaxYear sets the Min year and vice versa. Easy to fix locally. I'm not sure what the procedure is to get it in a future release.
public function setMaxYear( $year ) { $this->minYear = (int) $year; }
public function setMinYear( $year ) { $this->maxYear = (int) $year; }