Bug or feature

[kinloth]

Hello everyone! How are you?

It's been many years since I last played. I opened arcade mode and the village was empty, but with several perks unlocked using essence.
But here's the thing: I played with my wife yesterday, and we managed to defeat the boss on the 4th floor (mechanical knight), but the portal to the next floor didn't appear, blocking progress.

This happened two times in a row. The question is whether this is some kind of bug (maybe due to the very old save) or if there's a missing prerequisite like a quest or advancing in story mode.
If it's a bug, I can try to gather more information such as logs and videos/screenshots to report it properly

 

[Own]

In either the bottom left or right corner there's a ledge jutting out, similar to the one on Gundam's shoulders or in Flying Fortress in Story Mode. You can jump down off of that. Perhaps it needs an arrow there, or little inspection symbol pop-up when nearby?

 

[kinloth]

Ahhh, we found it thanks to your help, thank you very much Own, we were able to proceed!

Yes, it would be interesting if there was some kind of highlight, at least a more striking color.