Items not showing up in the "stuff I found" page

[Anthony Benedettini]

I don't know if this is a common bug or not, but I've been trying for a while to get the "real platinum gold" achievement but even though all the items necessary, there are several items that don't show up in the "stuff I found" page. Moreover, I've already picked up in previous runs many of those items that do not show up and I don't have any mods on. Does anyone know what's causing this issue?

[Nazemec]

The item list (also known as the Collection Page) does not show unlocked items, it shows items you picked at least once.
The Real Plat God achievement only refers to Rebirth content. If you have expansions installed, items from those expansions aren't required for this achievement.


Adding an item in the list is considered as progress, so if you've found an item within one of those situations it will not be added to the list.
List of things that prevent all kind of progress:
- Seeds (except a few special ones)
- Challenges (except for their reward obviously).
- Daily Runs.
- Reruns and Victory Laps (except for a few specific unlocks).
- Any active mod from the mod menu before Mom is killed once on that save (no matter what they do, other saves are irrelevant).
- Paranoid antivirus programs (or missing rights) preventing the game from creating/editing its save file.