Quietus II doesn't save progress when launched using desktop app

[rgally]

Describe the bug

Level select screen only allows to select level 1 after unlocking a few levels and reloading the swf file

Expected behavior

All unlocked levels should stay unlocked after reloading

Content Location

https://www.newgrounds.com/portal/view/601856
https://uploads.ungrounded.net/601000/601856_QuietusII.swf?1346159466

Affected platform

Desktop app

Operating system

Voidlinux

Browser

No response

Additional information

Unlike the desktop app, both Adobe's old standalone flashplayer and Ruffle extension for Firefox behave correctly, although the latter suffers significant performance problems (as does desktop app unless you set quality to Low).
Desktop app doesn't create SharedObjects folder for the swf in question — neither .local/share/ruffle/SharedObjects/$insert_path_here/601856_QuietusII.swf/ for local build nor ~/.var/app/rs.ruffle.Ruffle/data/ruffle/SharedObjects/$insert_path_here/601856_QuietusII.swf/ for flatpak version. If the folder in question already exists, desktop app doesn't create QuietusII.sol file in it. If QuietusII.sol file already exists (taken from a game with a few levels already unlocked), the previously unlocked levels stay unlocked after reloading but newly unlocked levels don't get saved. Finally, pressing C on level select screen to clear save file works correctly and removes QuietusII.sol file if it exists.