New upgrade won't open .ODT files in Mint 21.1

I just upgraded to Linux Mint 21.1 and the Flatpack version of Libre Office at the same time. Now Writer will not open my .odt files. I can create new files, but when I try and open them it brings up a ‘filter selection box’ containing only “ 1.0 Chart…ODF Chart…Help Content…” as choices. It then opens a chart page. My previous version of LO 6.xx worked fine. I tried to uninstall and redo the installation, but it tells me it can’t uninstall since other programs require LO files as dependencies. How to I access all my .odt files, and how do I fix this problem