It's fairly common knowledge that altering a variable can break saves which is why you frequently get saves prior to x.xx not compatible or similar in OPs. The ext editions, by adding scenes that take place before the end point of the standard edition, do exactly that so it should be assumed by players who've been around a while that this is the case unless stated otherwise (I personally would add it to the changelog, something that wasn't done for 2.2.24)
It's also fairly likely that, with 335 pages and, prior to your post, 6,688 replies that this question has been answered multiple times but, because people can't be arsed to search (and because thread regulars who can answer are sick of the same questions coming up all the time) anyone who does search can't find the answer anymore