header freeze hiding extra rows

I'm having trouble with frozen headers. When I'm not actively editing my spread sheet the frozen header and columns behave as intended. However as soon as I try to edit the sheet, the first two rows after the frozen header lines (2) also disappear; the first completely the second partially. The graphics of the row that partially disappears are the same as if i was scrolling and hiding / covering rows intentionally. Scrolling does not make them reappear. I've turned off and on the freeze option(s), duplicated the sheet with and without the freeze option(s) on, only thing that makes them reappear is clicking outside of the spread sheet. I've been using this spread sheet since January, and the problem just started June 19. I am running Numbers v 3.5.3 (2150), in OS X Yosemite v 10.10.4, iMac (27-inch, Late 2013).