Trouble saving to existing file on network share.

I am unable to save as a .xls on a network share. If I create a new document and try and save it as an xls to the share, it works. If I open that file, I can edit and save. If I open a word file, I can edit and save.

What I cannot do, is open an existing Excel file, edit and save. It goes through all the motions but does not actually save.

Version: 6.0.6.2
Build ID: 1:6.0.6-0ubuntu0.18.04.1
CPU threads: 4; OS: Linux 4.15; UI render: default; VCL: gtk3;
Locale: en-US (en_US.UTF-8); Calc: group

Anyone have any ideas how to resolve this?