I'm not aware of any such changes to GW mechanisms. That would require a pretty obvious update and announcement. There is a trend in facing smaller and smaller guilds which exacerbates an existing issue. Also Customer Service notoriously doesn't understand the game and has been giving some misleading responses. So let me try to explain all of what's going on.
I can verify correct behavior w my own gw record:
We had 8 defensive battles logged thus far. This is a maximum of 24 potential defense fights.
I have a sum total of 14 Losses. There's one Win which resulted in a surving line, all others were ultimately defeated. All personal defenses can be matched to finished battles, nothing is pending.
I have 7 total Surviving Lines. So in two battles I was "never attacked" and received credit for that. But there's still 3 of the potential fights not accounted for. So what gives?
There's two different kinds of "never attacked". (this is the part CS is getting confused). If you notice the guild CCCP in our history, I was "never attacked" by this guild. While they have 40+ members, this week they seem to have only 28 opt-in. On the rare occasion someone is nice enough to show me screencaps of our defenses I'm typically around #30-32. So when we are attacked by 28 ppl, my tower is not even on the field. So ofc in such a fight I'm "never attacked", I can't be. But these don't get credited as "surviving", they just don't exist.