I had been replaying the series up to this point, midway through Blackwell Convergence, to check the quality of some Spanish translation patches and have been able to do so until today. As of late I hadn't been able to play much at all, but had seen that the game had been supposedly updating many times recently (patch 2.2.1? Can anyone confirm if this is really a new patch?), and now it won't ever open again.

I was thinking of uninstalling it completely and cleaning the local files, but when I uninstalled and reinstalled, I left the savegames and... not only did that not fix the problem, but I can't seem to find the save files.

Has anyone experienced a similar problem? Thanks in advance!

Latest patch version for me seems to be 2.3(a)
Galaxy shows this version label in the View patch notes item, but the notes themselves show last changelog from 2.2.1.

I can launch the game without issues from within Galaxy, or without Galaxy (from the .exe file, not the shortcut) and also via ScummVM (although ScummVM detects it as an unknown variant of the game, since it has been updated).

I don't know about the issue of savegame file loss, sorry.
Mine (new ones) are created in C:\Users\<username>\Saved Games\Blackwell Convergence
where <username> is my Windows user name.
Maybe the old ones where saved elsewhere, or are incombatible with this new version. edit: On the thread about the changelog, it says that older save games should play fine, maybe with minor sound issues (https://www.gog.com/forum/blackwell_series/blackwell_series_changelog)