Saving after setting 'Freeze Rows and Columns' works only so long as the bottom edge of the window is clear of the row immediately below the frozen pane. Rows become unfrozen if the bottom of window encroaches into the row next to the frozen pane at time of saving. Further, if at any time the bottom or right window frames are dragged into the frozen pane they immediately unfreeze the rows or columns, respectively. This occurs in xlsx and ods formats, in 184.108.40.206 and 220.127.116.11 releases (haven't tried other releases), running under MacOS 10.12.6.
Can you provide us with a test document with which to test ?
Does it depend on the number of rows of data in the sheet, or any other objects included ?
@Duncan OK, don't bother with the file, I can reproduce this one easily with
Build ID: 0f28c8612f4269cec95688b53d182c7c0169236d
CPU threads: 4; OS: Mac OS X 10.13.3; UI render: default;
Locale: fr-FR (fr_FR.UTF-8); Calc: group threaded
Alex, apologies for my slow response. Glad you were able to duplicate the problem in the absence of a file from me. Good luck with a fix.
*** This bug has been marked as a duplicate of bug 112641 ***