There was a bug in the US Xbox version with overwriting saves, but it was a different problem (character location could be altered when reloading a save that had been overwritten). The source of the problem on the PC could be similar, though that wouldn't necessarily mean the solution was.
Larian can not create a patch, test it in-house and release it on their own, due presumably to the agreements they have with the various publishers.
From the old topic
Next patch (referring to the 1.03 patch, already released except for non-US Xbox versions):
Trust me, it's frustrating as hell for us too - I remember when we could build patches and release them the next day, allowing us to react very fast to whatever problems were encountered and quickly helping out if something went wrong. Now, for a million reasons, everything takes eternities before it gets from us to you.
If you needed to do something that would take a month (and delay other work), but you knew in 3 or 4 months you would have to do the entire thing over again (including the cost), would you do it now or wait?
Larian is continuing to optimize the game, make balancing changes and fix bugs in the main game as they are working on the add-on. In order to release a patch, they would have to finalize a version of the code to stop making feature changes to, and then start testing it (either instead of or parallel to work on the add-on and additional main game changes). Once they finish testing, that code has to go out to all the publishers to integrate into their versions, after which they would then need to test it using new and previous saves. At least some of the publishers use third party quality assurance companies to do some of the testing and support.
While faster patch releases would be nice, I can see where the publishers would want to wait until pretty much all the changes had been made and test everything at once.
While this bug can cause major problems, it has a very simple workaround to avoid it, if it occurs on your system...