Love this game and the cgs, however the bug did bother me as well.
So somehow, I can not view the IFS washroom CG as well, in both Chap 1 nor Chap 2. If I try to view it with main character, it would cause the final fight, and losing it (as I must) would lead to end of the game, which is acceptable because I could choose to go before the fight (3F) when I'm not suppose to be and give me access to posters a bit earlier. You can proceed the story without touching that CG as main character, so I continued to Chap2 with no problem, probably wouldn't have any problem going further.
However, the problem hits hard when I used the janitor to watch that CG and touch the pink circle. It directly lead to the CG that I beat Shizuka (probably in the end), I can decide to kill someone or just leave it as it be, IDK what to do and hit leave it, and directly cleared route C, which I still want to explore and experience.
So even though I do have to clear route B and C before the true end, I got fast-tracked...I'm pretty sure developer made this as some loophole for testers (to quickly get to true route, which requires most recent testing...if they tested by B/C then true route), but it just accidentally happened on us....
** I patched the game and this bug is entirely fixed, so yea it is written on the caption