1. Select rows 1-5 in an empty spreadsheet. 2. Select menu Data -> Group and Outline -> Group... (or press F12). 3. Click [-] sign in front of row 1 to collapse rows. 4. Save, close and reopen spreadsheet. Rows 2-4 are visible (not collapsed), 5 is not. Collapsing and uncollapsing rows uncollapses 5 as well. Row 1 remains hidden, as described in bug 102154 (that is a different issue). Reproduced with v5.2.0.1, v5.2.1.2 / Windows 7; v5.2.1.2 / Ubuntu 16.04. Not reproduced with v5.1.5.2 / Ubuntu 16.04. => regression
*** This bug has been marked as a duplicate of bug 101843 ***