It's seems like Saphura's room is quite buggy...
^^ (A screenshot from the gallery) ^^
^^ (A screenshot of an actual completion, and yes, they are completely solid and I'm unable to interact with Saphura nor his chests) ^^
At first I thought maybe this happened because I had viewed his scene from Shiptown (I thought the problem was that because Fucko wasn't the party in Shiptown, and that might've broken something), but, when I loaded a save where I never viewed the scene in any gallery and try to use the Piratetown gallery instead (where Fucko's clearly there), but still, same thing. Either way, when I tried to complete the water dungeon again, but, as seen from the screenshot, The way is blocked (why were they solid anyways??).
So okay, Just don't view Saphura's gallery then, but when I loaded a save where I NEVER viewed any gallery scene (but had entered the building to check gallery progression) I STILL couldn't complete the water dungeon. I had noticed this bug since 0.20 (maybe 0.19, but I can't remember, most probably 0.20 I think). And, if you're wondering, no, I didn't use an old save file, I made a whole new playthrough in 0.21 lasting a whole 22 hours, where I had completed what Paradino had to offer right now in the public build, and I was just trying to see if this bug is still happening at the end of it. Seems like it still is. Imagine my frustration back then.
It's a pretty weird bug... I wonder when it actually happened, was it after the third dungeon win and the first time seeing Saphura's scene? Was it because of the gallery and now it spread to other saves? I don't want to test any more because it is so tedious (because the dungeons are so tedious to go through I've done it five times just for this testing and I feel like I'm losing my mind).
(also, ignore the grove icon the window)